new file mode 100644
--- /dev/null
+++ b/src/viewport.cpp
@@ -0,0 +1,2462 @@
+/* $Id$ */
+
+#include "stdafx.h"
+#include "openttd.h"
+#include "debug.h"
+#include "functions.h"
+#include "gui.h"
+#include "spritecache.h"
+#include "strings.h"
+#include "table/sprites.h"
+#include "table/strings.h"
+#include "map.h"
+#include "viewport.h"
+#include "window.h"
+#include "vehicle.h"
+#include "station.h"
+#include "gfx.h"
+#include "town.h"
+#include "signs.h"
+#include "waypoint.h"
+#include "variables.h"
+#include "train.h"
+
+#define VIEWPORT_DRAW_MEM (65536 * 2)
+
+/* viewport.c */
+// XXX - maximum viewports is maximum windows - 2 (main toolbar + status bar)
+static ViewPort _viewports[25 - 2];
+static uint32 _active_viewports;    ///< bitmasked variable where each bit signifies if a viewport is in use or not
+assert_compile(lengthof(_viewports) < sizeof(_active_viewports) * 8);
+
+static bool _added_tile_sprite;
+static bool _offset_ground_sprites;
+
+/* The in-game coordiante system looks like this *
+ *                                               *
+ *                    ^ Z                        *
+ *                    |                          *
+ *                    |                          *
+ *                    |                          *
+ *                    |                          *
+ *                 /     \                       *
+ *              /           \                    *
+ *           /                 \                 *
+ *        /                       \              *
+ *   X <                             > Y         *
+ */
+
+typedef struct StringSpriteToDraw {
+	uint16 string;
+	uint16 color;
+	struct StringSpriteToDraw *next;
+	int32 x;
+	int32 y;
+	uint32 params[2];
+	uint16 width;
+} StringSpriteToDraw;
+
+typedef struct TileSpriteToDraw {
+	uint32 image;
+	struct TileSpriteToDraw *next;
+	int32 x;
+	int32 y;
+	byte z;
+} TileSpriteToDraw;
+
+typedef struct ChildScreenSpriteToDraw {
+	uint32 image;
+	int32 x;
+	int32 y;
+	struct ChildScreenSpriteToDraw *next;
+} ChildScreenSpriteToDraw;
+
+typedef struct ParentSpriteToDraw {
+	uint32 image;
+	int32 left;
+	int32 top;
+	int32 right;
+	int32 bottom;
+	int32 xmin;
+	int32 ymin;
+	int32 xmax;
+	int32 ymax;
+	ChildScreenSpriteToDraw *child;
+	byte unk16;
+	byte zmin;
+	byte zmax;
+} ParentSpriteToDraw;
+
+// Quick hack to know how much memory to reserve when allocating from the spritelist
+// to prevent a buffer overflow.
+#define LARGEST_SPRITELIST_STRUCT ParentSpriteToDraw
+
+typedef struct ViewportDrawer {
+	DrawPixelInfo dpi;
+
+	byte *spritelist_mem;
+	const byte *eof_spritelist_mem;
+
+	StringSpriteToDraw **last_string, *first_string;
+	TileSpriteToDraw **last_tile, *first_tile;
+
+	ChildScreenSpriteToDraw **last_child;
+
+	ParentSpriteToDraw **parent_list;
+	ParentSpriteToDraw * const *eof_parent_list;
+
+	byte combine_sprites;
+
+	int offs_x, offs_y; // used when drawing ground sprites relative
+} ViewportDrawer;
+
+static ViewportDrawer *_cur_vd;
+
+TileHighlightData _thd;
+static TileInfo *_cur_ti;
+
+extern void SmallMapCenterOnCurrentPos(Window *w);
+
+static Point MapXYZToViewport(const ViewPort *vp, uint x, uint y, uint z)
+{
+	Point p = RemapCoords(x, y, z);
+	p.x -= vp->virtual_width / 2;
+	p.y -= vp->virtual_height / 2;
+	return p;
+}
+
+void InitViewports(void) {
+	memset(_viewports, 0, sizeof(_viewports));
+	_active_viewports = 0;
+}
+
+void DeleteWindowViewport(Window *w)
+{
+	CLRBIT(_active_viewports, w->viewport - _viewports);
+	w->viewport->width = 0;
+	w->viewport = NULL;
+}
+
+void AssignWindowViewport(Window *w, int x, int y,
+	int width, int height, uint32 follow_flags, byte zoom)
+{
+	ViewPort *vp;
+	Point pt;
+	uint32 bit;
+
+	for (vp = _viewports, bit = 0; ; vp++, bit++) {
+		assert(vp != endof(_viewports));
+		if (vp->width == 0) break;
+	}
+	SETBIT(_active_viewports, bit);
+
+	vp->left = x + w->left;
+	vp->top = y + w->top;
+	vp->width = width;
+	vp->height = height;
+
+	vp->zoom = zoom;
+
+	vp->virtual_width = width << zoom;
+	vp->virtual_height = height << zoom;
+
+	if (follow_flags & 0x80000000) {
+		const Vehicle *veh;
+
+		WP(w, vp_d).follow_vehicle = (VehicleID)(follow_flags & 0xFFFF);
+		veh = GetVehicle(WP(w, vp_d).follow_vehicle);
+		pt = MapXYZToViewport(vp, veh->x_pos, veh->y_pos, veh->z_pos);
+	} else {
+		uint x = TileX(follow_flags) * TILE_SIZE;
+		uint y = TileY(follow_flags) * TILE_SIZE;
+
+		WP(w, vp_d).follow_vehicle = INVALID_VEHICLE;
+		pt = MapXYZToViewport(vp, x, y, GetSlopeZ(x, y));
+	}
+
+	WP(w, vp_d).scrollpos_x = pt.x;
+	WP(w, vp_d).scrollpos_y = pt.y;
+	w->viewport = vp;
+	vp->virtual_left = 0;//pt.x;
+	vp->virtual_top = 0;//pt.y;
+}
+
+static Point _vp_move_offs;
+
+static void DoSetViewportPosition(Window* const *wz, int left, int top, int width, int height)
+{
+
+	for (; wz != _last_z_window; wz++) {
+		const Window *w = *wz;
+
+		if (left + width > w->left &&
+				w->left + w->width > left &&
+				top + height > w->top &&
+				w->top + w->height > top) {
+
+			if (left < w->left) {
+				DoSetViewportPosition(wz, left, top, w->left - left, height);
+				DoSetViewportPosition(wz, left + (w->left - left), top, width - (w->left - left), height);
+				return;
+			}
+
+			if (left + width > w->left + w->width) {
+				DoSetViewportPosition(wz, left, top, (w->left + w->width - left), height);
+				DoSetViewportPosition(wz, left + (w->left + w->width - left), top, width - (w->left + w->width - left) , height);
+				return;
+			}
+
+			if (top < w->top) {
+				DoSetViewportPosition(wz, left, top, width, (w->top - top));
+				DoSetViewportPosition(wz, left, top + (w->top - top), width, height - (w->top - top));
+				return;
+			}
+
+			if (top + height > w->top + w->height) {
+				DoSetViewportPosition(wz, left, top, width, (w->top + w->height - top));
+				DoSetViewportPosition(wz, left, top + (w->top + w->height - top), width , height - (w->top + w->height - top));
+				return;
+			}
+
+			return;
+		}
+	}
+
+	{
+		int xo = _vp_move_offs.x;
+		int yo = _vp_move_offs.y;
+
+		if (abs(xo) >= width || abs(yo) >= height) {
+			/* fully_outside */
+			RedrawScreenRect(left, top, left + width, top + height);
+			return;
+		}
+
+		GfxScroll(left, top, width, height, xo, yo);
+
+		if (xo > 0) {
+			RedrawScreenRect(left, top, xo + left, top + height);
+			left += xo;
+			width -= xo;
+		} else if (xo < 0) {
+			RedrawScreenRect(left+width+xo, top, left+width, top + height);
+			width += xo;
+		}
+
+		if (yo > 0) {
+			RedrawScreenRect(left, top, width+left, top + yo);
+		} else if (yo < 0) {
+			RedrawScreenRect(left, top + height + yo, width+left, top + height);
+		}
+	}
+}
+
+static void SetViewportPosition(Window *w, int x, int y)
+{
+	ViewPort *vp = w->viewport;
+	int old_left = vp->virtual_left;
+	int old_top = vp->virtual_top;
+	int i;
+	int left, top, width, height;
+
+	vp->virtual_left = x;
+	vp->virtual_top = y;
+
+	old_left >>= vp->zoom;
+	old_top >>= vp->zoom;
+	x >>= vp->zoom;
+	y >>= vp->zoom;
+
+	old_left -= x;
+	old_top -= y;
+
+	if (old_top == 0 && old_left == 0) return;
+
+	_vp_move_offs.x = old_left;
+	_vp_move_offs.y = old_top;
+
+	left = vp->left;
+	top = vp->top;
+	width = vp->width;
+	height = vp->height;
+
+	if (left < 0) {
+		width += left;
+		left = 0;
+	}
+
+	i = left + width - _screen.width;
+	if (i >= 0) width -= i;
+
+	if (width > 0) {
+		if (top < 0) {
+			height += top;
+			top = 0;
+		}
+
+		i = top + height - _screen.height;
+		if (i >= 0) height -= i;
+
+		if (height > 0) DoSetViewportPosition(FindWindowZPosition(w) + 1, left, top, width, height);
+	}
+}
+
+
+ViewPort *IsPtInWindowViewport(const Window *w, int x, int y)
+{
+	ViewPort *vp = w->viewport;
+
+	if (vp != NULL &&
+	    IS_INT_INSIDE(x, vp->left, vp->left + vp->width) &&
+			IS_INT_INSIDE(y, vp->top, vp->top + vp->height))
+		return vp;
+
+	return NULL;
+}
+
+static Point TranslateXYToTileCoord(const ViewPort *vp, int x, int y)
+{
+	Point pt;
+	int a,b;
+	uint z;
+
+	if ( (uint)(x -= vp->left) >= (uint)vp->width ||
+				(uint)(y -= vp->top) >= (uint)vp->height) {
+				Point pt = {-1, -1};
+				return pt;
+	}
+
+	x = ((x << vp->zoom) + vp->virtual_left) >> 2;
+	y = ((y << vp->zoom) + vp->virtual_top) >> 1;
+
+	a = y-x;
+	b = y+x;
+
+	/* we need to move variables in to the valid range, as the
+	 * GetTileZoomCenterWindow() function can call here with invalid x and/or y,
+	 * when the user tries to zoom out along the sides of the map */
+	a = clamp(a, 0, (int)(MapMaxX() * TILE_SIZE) - 1);
+	b = clamp(b, 0, (int)(MapMaxY() * TILE_SIZE) - 1);
+
+	z = GetSlopeZ(a,     b    ) / 2;
+	z = GetSlopeZ(a + z, b + z) / 2;
+	z = GetSlopeZ(a + z, b + z) / 2;
+	z = GetSlopeZ(a + z, b + z) / 2;
+	z = GetSlopeZ(a + z, b + z) / 2;
+
+	pt.x = a + z;
+	pt.y = b + z;
+
+	return pt;
+}
+
+/* When used for zooming, check area below current coordinates (x,y)
+ * and return the tile of the zoomed out/in position (zoom_x, zoom_y)
+ * when you just want the tile, make x = zoom_x and y = zoom_y */
+static Point GetTileFromScreenXY(int x, int y, int zoom_x, int zoom_y)
+{
+	Window *w;
+	ViewPort *vp;
+	Point pt;
+
+	if ( (w = FindWindowFromPt(x, y)) != NULL &&
+			 (vp = IsPtInWindowViewport(w, x, y)) != NULL)
+				return TranslateXYToTileCoord(vp, zoom_x, zoom_y);
+
+	pt.y = pt.x = -1;
+	return pt;
+}
+
+Point GetTileBelowCursor(void)
+{
+	return GetTileFromScreenXY(_cursor.pos.x, _cursor.pos.y, _cursor.pos.x, _cursor.pos.y);
+}
+
+
+Point GetTileZoomCenterWindow(bool in, Window * w)
+{
+	int x, y;
+	ViewPort * vp;
+
+	vp = w->viewport;
+
+	if (in) {
+		x = ((_cursor.pos.x - vp->left) >> 1) + (vp->width >> 2);
+		y = ((_cursor.pos.y - vp->top) >> 1) + (vp->height >> 2);
+	} else {
+		x = vp->width - (_cursor.pos.x - vp->left);
+		y = vp->height - (_cursor.pos.y - vp->top);
+	}
+	/* Get the tile below the cursor and center on the zoomed-out center */
+	return GetTileFromScreenXY(_cursor.pos.x, _cursor.pos.y, x + vp->left, y + vp->top);
+}
+
+/** Update the status of the zoom-buttons according to the zoom-level
+ * of the viewport. This will update their status and invalidate accordingly
+ * @param window pointer to the window that has the zoom buttons
+ * @param vp pointer to the viewport whose zoom-level the buttons represent
+ * @param widget_zoom_in widget index for window with zoom-in button
+ * @param widget_zoom_out widget index for window with zoom-out button */
+void HandleZoomMessage(Window *w, const ViewPort *vp, byte widget_zoom_in, byte widget_zoom_out)
+{
+	SetWindowWidgetDisabledState(w, widget_zoom_in, vp->zoom == 0);
+	InvalidateWidget(w, widget_zoom_in);
+
+	SetWindowWidgetDisabledState(w, widget_zoom_out, vp->zoom == 2);
+	InvalidateWidget(w, widget_zoom_out);
+}
+
+void DrawGroundSpriteAt(uint32 image, int32 x, int32 y, byte z)
+{
+	ViewportDrawer *vd = _cur_vd;
+	TileSpriteToDraw *ts;
+
+	assert((image & SPRITE_MASK) < MAX_SPRITES);
+
+	if (vd->spritelist_mem >= vd->eof_spritelist_mem) {
+		DEBUG(sprite, 0, "Out of sprite memory");
+		return;
+	}
+	ts = (TileSpriteToDraw*)vd->spritelist_mem;
+
+	vd->spritelist_mem += sizeof(TileSpriteToDraw);
+
+	ts->image = image;
+	ts->next = NULL;
+	ts->x = x;
+	ts->y = y;
+	ts->z = z;
+	*vd->last_tile = ts;
+	vd->last_tile = &ts->next;
+}
+
+void DrawGroundSprite(uint32 image)
+{
+	if (_offset_ground_sprites) {
+		// offset ground sprite because of foundation?
+		AddChildSpriteScreen(image, _cur_vd->offs_x, _cur_vd->offs_y);
+	} else {
+		_added_tile_sprite = true;
+		DrawGroundSpriteAt(image, _cur_ti->x, _cur_ti->y, _cur_ti->z);
+	}
+}
+
+
+void OffsetGroundSprite(int x, int y)
+{
+	_cur_vd->offs_x = x;
+	_cur_vd->offs_y = y;
+	_offset_ground_sprites = true;
+}
+
+static void AddCombinedSprite(uint32 image, int x, int y, byte z)
+{
+	const ViewportDrawer *vd = _cur_vd;
+	Point pt = RemapCoords(x, y, z);
+	const Sprite* spr = GetSprite(image & SPRITE_MASK);
+
+	if (pt.x + spr->x_offs >= vd->dpi.left + vd->dpi.width ||
+			pt.x + spr->x_offs + spr->width <= vd->dpi.left ||
+			pt.y + spr->y_offs >= vd->dpi.top + vd->dpi.height ||
+			pt.y + spr->y_offs + spr->height <= vd->dpi.top)
+		return;
+
+	AddChildSpriteScreen(image, pt.x - vd->parent_list[-1]->left, pt.y - vd->parent_list[-1]->top);
+}
+
+
+void AddSortableSpriteToDraw(uint32 image, int x, int y, int w, int h, byte dz, byte z)
+{
+	ViewportDrawer *vd = _cur_vd;
+	ParentSpriteToDraw *ps;
+	const Sprite *spr;
+	Point pt;
+
+	assert((image & SPRITE_MASK) < MAX_SPRITES);
+
+	if (vd->combine_sprites == 2) {
+		AddCombinedSprite(image, x, y, z);
+		return;
+	}
+
+	vd->last_child = NULL;
+
+	if (vd->spritelist_mem >= vd->eof_spritelist_mem) {
+		DEBUG(sprite, 0, "Out of sprite memory");
+		return;
+	}
+	ps = (ParentSpriteToDraw*)vd->spritelist_mem;
+
+	if (vd->parent_list >= vd->eof_parent_list) {
+		// This can happen rarely, mostly when you zoom out completely
+		//  and have a lot of stuff that moves (and is added to the
+		//  sort-list, this function). To solve it, increase
+		//  parent_list somewhere below to a higher number.
+		// This can not really hurt you, it just gives some black
+		//  spots on the screen ;)
+		DEBUG(sprite, 0, "Out of sprite memory (parent_list)");
+		return;
+	}
+
+	pt = RemapCoords(x, y, z);
+	spr = GetSprite(image & SPRITE_MASK);
+	if ((ps->left   = (pt.x += spr->x_offs)) >= vd->dpi.left + vd->dpi.width ||
+			(ps->right  = (pt.x +  spr->width )) <= vd->dpi.left ||
+			(ps->top    = (pt.y += spr->y_offs)) >= vd->dpi.top + vd->dpi.height ||
+			(ps->bottom = (pt.y +  spr->height)) <= vd->dpi.top) {
+		return;
+	}
+
+	vd->spritelist_mem += sizeof(ParentSpriteToDraw);
+
+	ps->image = image;
+	ps->xmin = x;
+	ps->xmax = x + w - 1;
+
+	ps->ymin = y;
+	ps->ymax = y + h - 1;
+
+	ps->zmin = z;
+	ps->zmax = z + dz - 1;
+
+	ps->unk16 = 0;
+	ps->child = NULL;
+	vd->last_child = &ps->child;
+
+	*vd->parent_list++ = ps;
+
+	if (vd->combine_sprites == 1) vd->combine_sprites = 2;
+}
+
+void StartSpriteCombine(void)
+{
+	_cur_vd->combine_sprites = 1;
+}
+
+void EndSpriteCombine(void)
+{
+	_cur_vd->combine_sprites = 0;
+}
+
+void AddChildSpriteScreen(uint32 image, int x, int y)
+{
+	ViewportDrawer *vd = _cur_vd;
+	ChildScreenSpriteToDraw *cs;
+
+	assert((image & SPRITE_MASK) < MAX_SPRITES);
+
+	if (vd->spritelist_mem >= vd->eof_spritelist_mem) {
+		DEBUG(sprite, 0, "Out of sprite memory");
+		return;
+	}
+	cs = (ChildScreenSpriteToDraw*)vd->spritelist_mem;
+
+	if (vd->last_child == NULL) return;
+
+	vd->spritelist_mem += sizeof(ChildScreenSpriteToDraw);
+
+	*vd->last_child = cs;
+	vd->last_child = &cs->next;
+
+	cs->image = image;
+	cs->x = x;
+	cs->y = y;
+	cs->next = NULL;
+}
+
+/* Returns a StringSpriteToDraw */
+void *AddStringToDraw(int x, int y, StringID string, uint32 params_1, uint32 params_2)
+{
+	ViewportDrawer *vd = _cur_vd;
+	StringSpriteToDraw *ss;
+
+	if (vd->spritelist_mem >= vd->eof_spritelist_mem) {
+		DEBUG(sprite, 0, "Out of sprite memory");
+		return NULL;
+	}
+	ss = (StringSpriteToDraw*)vd->spritelist_mem;
+
+	vd->spritelist_mem += sizeof(StringSpriteToDraw);
+
+	ss->string = string;
+	ss->next = NULL;
+	ss->x = x;
+	ss->y = y;
+	ss->params[0] = params_1;
+	ss->params[1] = params_2;
+	ss->width = 0;
+
+	*vd->last_string = ss;
+	vd->last_string = &ss->next;
+
+	return ss;
+}
+
+
+static void DrawSelectionSprite(uint32 image, const TileInfo *ti)
+{
+	if (_added_tile_sprite && !(_thd.drawstyle & HT_LINE)) { // draw on real ground
+		DrawGroundSpriteAt(image, ti->x, ti->y, ti->z + 7);
+	} else { // draw on top of foundation
+		AddSortableSpriteToDraw(image, ti->x, ti->y, 0x10, 0x10, 1, ti->z + 7);
+	}
+}
+
+static bool IsPartOfAutoLine(int px, int py)
+{
+	px -= _thd.selstart.x;
+	py -= _thd.selstart.y;
+
+	switch (_thd.drawstyle) {
+	case HT_LINE | HT_DIR_X:  return py == 0; // x direction
+	case HT_LINE | HT_DIR_Y:  return px == 0; // y direction
+	case HT_LINE | HT_DIR_HU: return px == -py || px == -py - 16; // horizontal upper
+	case HT_LINE | HT_DIR_HL: return px == -py || px == -py + 16; // horizontal lower
+	case HT_LINE | HT_DIR_VL: return px == py || px == py + 16; // vertival left
+	case HT_LINE | HT_DIR_VR: return px == py || px == py - 16; // vertical right
+	default:
+		NOT_REACHED();
+	}
+
+	/* useless, but avoids compiler warning this way */
+	return 0;
+}
+
+// [direction][side]
+static const int _AutorailType[6][2] = {
+	{ HT_DIR_X,  HT_DIR_X },
+	{ HT_DIR_Y,  HT_DIR_Y },
+	{ HT_DIR_HU, HT_DIR_HL },
+	{ HT_DIR_HL, HT_DIR_HU },
+	{ HT_DIR_VL, HT_DIR_VR },
+	{ HT_DIR_VR, HT_DIR_VL }
+};
+
+#include "table/autorail.h"
+
+static void DrawTileSelection(const TileInfo *ti)
+{
+	uint32 image;
+
+	// Draw a red error square?
+	if (_thd.redsq != 0 && _thd.redsq == ti->tile) {
+		DrawSelectionSprite(PALETTE_TILE_RED_PULSATING | (SPR_SELECT_TILE + _tileh_to_sprite[ti->tileh]), ti);
+		return;
+	}
+
+	// no selection active?
+	if (_thd.drawstyle == 0) return;
+
+	// Inside the inner area?
+	if (IS_INSIDE_1D(ti->x, _thd.pos.x, _thd.size.x) &&
+			IS_INSIDE_1D(ti->y, _thd.pos.y, _thd.size.y)) {
+		if (_thd.drawstyle & HT_RECT) {
+			image = SPR_SELECT_TILE + _tileh_to_sprite[ti->tileh];
+			if (_thd.make_square_red) image |= PALETTE_SEL_TILE_RED;
+			DrawSelectionSprite(image, ti);
+		} else if (_thd.drawstyle & HT_POINT) {
+			// Figure out the Z coordinate for the single dot.
+			byte z = ti->z;
+			if (ti->tileh & SLOPE_N) {
+				z += TILE_HEIGHT;
+				if (ti->tileh == SLOPE_STEEP_N) z += TILE_HEIGHT;
+			}
+			DrawGroundSpriteAt(_cur_dpi->zoom != 2 ? SPR_DOT : SPR_DOT_SMALL, ti->x, ti->y, z);
+		} else if (_thd.drawstyle & HT_RAIL /*&& _thd.place_mode == VHM_RAIL*/) {
+			// autorail highlight piece under cursor
+			uint type = _thd.drawstyle & 0xF;
+			assert(type <= 5);
+			image = SPR_AUTORAIL_BASE + _AutorailTilehSprite[ti->tileh][_AutorailType[type][0]];
+
+			if (_thd.make_square_red) image |= PALETTE_SEL_TILE_RED;
+			DrawSelectionSprite(image, ti);
+
+		} else if (IsPartOfAutoLine(ti->x, ti->y)) {
+			// autorail highlighting long line
+			int dir = _thd.drawstyle & ~0xF0;
+			uint side;
+
+			if (dir < 2) {
+				side = 0;
+			} else {
+				TileIndex start = TileVirtXY(_thd.selstart.x, _thd.selstart.y);
+				int diffx = myabs(TileX(start) - TileX(ti->tile));
+				int diffy = myabs(TileY(start) - TileY(ti->tile));
+				side = myabs(diffx - diffy);
+			}
+
+			image = SPR_AUTORAIL_BASE + _AutorailTilehSprite[ti->tileh][_AutorailType[dir][side]];
+
+			if (_thd.make_square_red) image |= PALETTE_SEL_TILE_RED;
+			DrawSelectionSprite(image, ti);
+		}
+		return;
+	}
+
+	// Check if it's inside the outer area?
+	if (_thd.outersize.x &&
+			_thd.size.x < _thd.size.x + _thd.outersize.x &&
+			IS_INSIDE_1D(ti->x, _thd.pos.x + _thd.offs.x, _thd.size.x + _thd.outersize.x) &&
+			IS_INSIDE_1D(ti->y, _thd.pos.y + _thd.offs.y, _thd.size.y + _thd.outersize.y)) {
+		// Draw a blue rect.
+		DrawSelectionSprite(PALETTE_SEL_TILE_BLUE | (SPR_SELECT_TILE + _tileh_to_sprite[ti->tileh]), ti);
+		return;
+	}
+}
+
+static void ViewportAddLandscape(void)
+{
+	ViewportDrawer *vd = _cur_vd;
+	int x, y, width, height;
+	TileInfo ti;
+	bool direction;
+
+	_cur_ti = &ti;
+
+	// Transform into tile coordinates and round to closest full tile
+	x = ((vd->dpi.top >> 1) - (vd->dpi.left >> 2)) & ~0xF;
+	y = ((vd->dpi.top >> 1) + (vd->dpi.left >> 2) - 0x10) & ~0xF;
+
+	// determine size of area
+	{
+		Point pt = RemapCoords(x, y, 241);
+		width = (vd->dpi.left + vd->dpi.width - pt.x + 95) >> 6;
+		height = (vd->dpi.top + vd->dpi.height - pt.y) >> 5 << 1;
+	}
+
+	assert(width > 0);
+	assert(height > 0);
+
+	direction = false;
+
+	do {
+		int width_cur = width;
+		int x_cur = x;
+		int y_cur = y;
+
+		do {
+			TileType tt;
+
+			ti.x = x_cur;
+			ti.y = y_cur;
+			if (0 <= x_cur && x_cur < (int)MapMaxX() * TILE_SIZE &&
+					0 <= y_cur && y_cur < (int)MapMaxY() * TILE_SIZE) {
+				TileIndex tile = TileVirtXY(x_cur, y_cur);
+
+				ti.tile = tile;
+				ti.tileh = GetTileSlope(tile, &ti.z);
+				tt = GetTileType(tile);
+			} else {
+				ti.tileh = SLOPE_FLAT;
+				ti.tile = 0;
+				ti.z = 0;
+				tt = MP_VOID;
+			}
+
+			y_cur += 0x10;
+			x_cur -= 0x10;
+
+			_added_tile_sprite = false;
+			_offset_ground_sprites = false;
+
+			_tile_type_procs[tt]->draw_tile_proc(&ti);
+			DrawTileSelection(&ti);
+		} while (--width_cur);
+
+		if ((direction ^= 1) != 0) {
+			y += 0x10;
+		} else {
+			x += 0x10;
+		}
+	} while (--height);
+}
+
+
+static void ViewportAddTownNames(DrawPixelInfo *dpi)
+{
+	Town *t;
+	int left, top, right, bottom;
+
+	if (!(_display_opt & DO_SHOW_TOWN_NAMES) || _game_mode == GM_MENU)
+		return;
+
+	left = dpi->left;
+	top = dpi->top;
+	right = left + dpi->width;
+	bottom = top + dpi->height;
+
+	switch (dpi->zoom) {
+		case 0:
+			FOR_ALL_TOWNS(t) {
+				if (bottom > t->sign.top &&
+						top    < t->sign.top + 12 &&
+						right  > t->sign.left &&
+						left   < t->sign.left + t->sign.width_1) {
+					AddStringToDraw(t->sign.left + 1, t->sign.top + 1,
+						_patches.population_in_label ? STR_TOWN_LABEL_POP : STR_TOWN_LABEL,
+						t->index, t->population);
+				}
+			}
+			break;
+
+		case 1:
+			right += 2;
+			bottom += 2;
+
+			FOR_ALL_TOWNS(t) {
+				if (bottom > t->sign.top &&
+						top    < t->sign.top + 24 &&
+						right  > t->sign.left &&
+						left   < t->sign.left + t->sign.width_1*2) {
+					AddStringToDraw(t->sign.left + 1, t->sign.top + 1,
+						_patches.population_in_label ? STR_TOWN_LABEL_POP : STR_TOWN_LABEL,
+						t->index, t->population);
+				}
+			}
+			break;
+
+		default: NOT_REACHED();
+		case 2:
+			right += 4;
+			bottom += 5;
+
+			FOR_ALL_TOWNS(t) {
+				if (bottom > t->sign.top &&
+						top    < t->sign.top + 24 &&
+						right  > t->sign.left &&
+						left   < t->sign.left + t->sign.width_2*4) {
+					AddStringToDraw(t->sign.left + 5, t->sign.top + 1, STR_TOWN_LABEL_TINY_BLACK, t->index, 0);
+					AddStringToDraw(t->sign.left + 1, t->sign.top - 3, STR_TOWN_LABEL_TINY_WHITE, t->index, 0);
+				}
+			}
+			break;
+	}
+}
+
+
+static void AddStation(const Station *st, StringID str, uint16 width)
+{
+	StringSpriteToDraw *sstd;
+
+	sstd = AddStringToDraw(st->sign.left + 1, st->sign.top + 1, str, st->index, st->facilities);
+	if (sstd != NULL) {
+		sstd->color = (st->owner == OWNER_NONE || st->facilities == 0) ? 0xE : _player_colors[st->owner];
+		sstd->width = width;
+	}
+}
+
+
+static void ViewportAddStationNames(DrawPixelInfo *dpi)
+{
+	int left, top, right, bottom;
+	const Station *st;
+
+	if (!(_display_opt & DO_SHOW_STATION_NAMES) || _game_mode == GM_MENU)
+		return;
+
+	left = dpi->left;
+	top = dpi->top;
+	right = left + dpi->width;
+	bottom = top + dpi->height;
+
+	switch (dpi->zoom) {
+		case 0:
+			FOR_ALL_STATIONS(st) {
+				if (bottom > st->sign.top &&
+						top    < st->sign.top + 12 &&
+						right  > st->sign.left &&
+						left   < st->sign.left + st->sign.width_1) {
+					AddStation(st, STR_305C_0, st->sign.width_1);
+				}
+			}
+			break;
+
+		case 1:
+			right += 2;
+			bottom += 2;
+			FOR_ALL_STATIONS(st) {
+				if (bottom > st->sign.top &&
+						top    < st->sign.top + 24 &&
+						right  > st->sign.left &&
+						left   < st->sign.left + st->sign.width_1*2) {
+					AddStation(st, STR_305C_0, st->sign.width_1);
+				}
+			}
+			break;
+
+		default: NOT_REACHED();
+		case 2:
+			right += 4;
+			bottom += 5;
+			FOR_ALL_STATIONS(st) {
+				if (bottom > st->sign.top &&
+						top    < st->sign.top + 24 &&
+						right  > st->sign.left &&
+						left   < st->sign.left + st->sign.width_2*4) {
+					AddStation(st, STR_STATION_SIGN_TINY, st->sign.width_2 | 0x8000);
+				}
+			}
+			break;
+	}
+}
+
+
+static void AddSign(const Sign *si, StringID str, uint16 width)
+{
+	StringSpriteToDraw *sstd;
+
+	sstd = AddStringToDraw(si->sign.left + 1, si->sign.top + 1, str, si->str, 0);
+	if (sstd != NULL) {
+		sstd->color = (si->owner == OWNER_NONE) ? 14 : _player_colors[si->owner];
+		sstd->width = width;
+	}
+}
+
+
+static void ViewportAddSigns(DrawPixelInfo *dpi)
+{
+	const Sign *si;
+	int left, top, right, bottom;
+
+	if (!(_display_opt & DO_SHOW_SIGNS))
+		return;
+
+	left = dpi->left;
+	top = dpi->top;
+	right = left + dpi->width;
+	bottom = top + dpi->height;
+
+	switch (dpi->zoom) {
+		case 0:
+			FOR_ALL_SIGNS(si) {
+				if (bottom > si->sign.top &&
+						top    < si->sign.top + 12 &&
+						right  > si->sign.left &&
+						left   < si->sign.left + si->sign.width_1) {
+					AddSign(si, STR_2806, si->sign.width_1);
+				}
+			}
+			break;
+
+		case 1:
+			right += 2;
+			bottom += 2;
+			FOR_ALL_SIGNS(si) {
+				if (bottom > si->sign.top &&
+						top    < si->sign.top + 24 &&
+						right  > si->sign.left &&
+						left   < si->sign.left + si->sign.width_1 * 2) {
+					AddSign(si, STR_2806, si->sign.width_1);
+				}
+			}
+			break;
+
+		default: NOT_REACHED();
+		case 2:
+			right += 4;
+			bottom += 5;
+			FOR_ALL_SIGNS(si) {
+				if (bottom > si->sign.top &&
+						top    < si->sign.top + 24 &&
+						right  > si->sign.left &&
+						left   < si->sign.left + si->sign.width_2 * 4) {
+					AddSign(si, STR_2002, si->sign.width_2 | 0x8000);
+				}
+			}
+			break;
+	}
+}
+
+
+static void AddWaypoint(const Waypoint *wp, StringID str, uint16 width)
+{
+	StringSpriteToDraw *sstd;
+
+	sstd = AddStringToDraw(wp->sign.left + 1, wp->sign.top + 1, str, wp->index, 0);
+	if (sstd != NULL) {
+		sstd->color = (wp->deleted ? 0xE : 11);
+		sstd->width = width;
+	}
+}
+
+
+static void ViewportAddWaypoints(DrawPixelInfo *dpi)
+{
+	const Waypoint *wp;
+	int left, top, right, bottom;
+
+	if (!(_display_opt & DO_WAYPOINTS))
+		return;
+
+	left = dpi->left;
+	top = dpi->top;
+	right = left + dpi->width;
+	bottom = top + dpi->height;
+
+	switch (dpi->zoom) {
+		case 0:
+			FOR_ALL_WAYPOINTS(wp) {
+				if (bottom > wp->sign.top &&
+						top    < wp->sign.top + 12 &&
+						right  > wp->sign.left &&
+						left   < wp->sign.left + wp->sign.width_1) {
+					AddWaypoint(wp, STR_WAYPOINT_VIEWPORT, wp->sign.width_1);
+				}
+			}
+			break;
+
+		case 1:
+			right += 2;
+			bottom += 2;
+			FOR_ALL_WAYPOINTS(wp) {
+				if (bottom > wp->sign.top &&
+						top    < wp->sign.top + 24 &&
+						right  > wp->sign.left &&
+						left   < wp->sign.left + wp->sign.width_1*2) {
+					AddWaypoint(wp, STR_WAYPOINT_VIEWPORT, wp->sign.width_1);
+				}
+			}
+			break;
+
+		default: NOT_REACHED();
+		case 2:
+			right += 4;
+			bottom += 5;
+			FOR_ALL_WAYPOINTS(wp) {
+				if (bottom > wp->sign.top &&
+						top    < wp->sign.top + 24 &&
+						right  > wp->sign.left &&
+						left   < wp->sign.left + wp->sign.width_2*4) {
+					AddWaypoint(wp, STR_WAYPOINT_VIEWPORT_TINY, wp->sign.width_2 | 0x8000);
+				}
+			}
+			break;
+	}
+}
+
+void UpdateViewportSignPos(ViewportSign *sign, int left, int top, StringID str)
+{
+	char buffer[128];
+	uint w;
+
+	sign->top = top;
+
+	GetString(buffer, str, lastof(buffer));
+	w = GetStringBoundingBox(buffer).width + 3;
+	sign->width_1 = w;
+	sign->left = left - w / 2;
+
+	/* zoomed out version */
+	_cur_fontsize = FS_SMALL;
+	w = GetStringBoundingBox(buffer).width + 3;
+	_cur_fontsize = FS_NORMAL;
+	sign->width_2 = w;
+}
+
+
+static void ViewportDrawTileSprites(TileSpriteToDraw *ts)
+{
+	do {
+		Point pt = RemapCoords(ts->x, ts->y, ts->z);
+		DrawSprite(ts->image, pt.x, pt.y);
+		ts = ts->next;
+	} while (ts != NULL);
+}
+
+static void ViewportSortParentSprites(ParentSpriteToDraw *psd[])
+{
+	while (*psd != NULL) {
+		ParentSpriteToDraw* ps = *psd;
+
+		if (!(ps->unk16 & 1)) {
+			ParentSpriteToDraw** psd2 = psd;
+
+			ps->unk16 |= 1;
+
+			while (*++psd2 != NULL) {
+				ParentSpriteToDraw* ps2 = *psd2;
+				ParentSpriteToDraw** psd3;
+
+				if (ps2->unk16 & 1) continue;
+
+				/* Decide which comparator to use, based on whether the bounding
+				 * boxes overlap
+				 */
+				if (ps->xmax > ps2->xmin && ps->xmin < ps2->xmax && // overlap in X?
+						ps->ymax > ps2->ymin && ps->ymin < ps2->ymax && // overlap in Y?
+						ps->zmax > ps2->zmin && ps->zmin < ps2->zmax) { // overlap in Z?
+					/* Use X+Y+Z as the sorting order, so sprites closer to the bottom of
+					 * the screen and with higher Z elevation, are drawn in front.
+					 * Here X,Y,Z are the coordinates of the "center of mass" of the sprite,
+					 * i.e. X=(left+right)/2, etc.
+					 * However, since we only care about order, don't actually divide / 2
+					 */
+					if (ps->xmin + ps->xmax + ps->ymin + ps->ymax + ps->zmin + ps->zmax <=
+							ps2->xmin + ps2->xmax + ps2->ymin + ps2->ymax + ps2->zmin + ps2->zmax) {
+						continue;
+					}
+				} else {
+					if (ps->xmax < ps2->xmin ||
+							ps->ymax < ps2->ymin ||
+							ps->zmax < ps2->zmin || (
+								ps->xmin < ps2->xmax &&
+								ps->ymin < ps2->ymax &&
+								ps->zmin < ps2->zmax
+							)) {
+						continue;
+					}
+				}
+
+				// Swap the two sprites ps and ps2 using bubble-sort algorithm.
+				psd3 = psd;
+				do {
+					ParentSpriteToDraw* temp = *psd3;
+					*psd3 = ps2;
+					ps2 = temp;
+
+					psd3++;
+				} while (psd3 <= psd2);
+			}
+		} else {
+			psd++;
+		}
+	}
+}
+
+static void ViewportDrawParentSprites(ParentSpriteToDraw *psd[])
+{
+	for (; *psd != NULL; psd++) {
+		const ParentSpriteToDraw* ps = *psd;
+		Point pt = RemapCoords(ps->xmin, ps->ymin, ps->zmin);
+		const ChildScreenSpriteToDraw* cs;
+
+		DrawSprite(ps->image, pt.x, pt.y);
+
+		for (cs = ps->child; cs != NULL; cs = cs->next) {
+			DrawSprite(cs->image, ps->left + cs->x, ps->top + cs->y);
+		}
+	}
+}
+
+static void ViewportDrawStrings(DrawPixelInfo *dpi, const StringSpriteToDraw *ss)
+{
+	DrawPixelInfo dp;
+	byte zoom;
+
+	_cur_dpi = &dp;
+	dp = *dpi;
+
+	zoom = dp.zoom;
+	dp.zoom = 0;
+
+	dp.left >>= zoom;
+	dp.top >>= zoom;
+	dp.width >>= zoom;
+	dp.height >>= zoom;
+
+	do {
+		uint16 colour;
+
+		if (ss->width != 0) {
+			int x = (ss->x >> zoom) - 1;
+			int y = (ss->y >> zoom) - 1;
+			int bottom = y + 11;
+			int w = ss->width;
+
+			if (w & 0x8000) {
+				w &= ~0x8000;
+				y--;
+				bottom -= 6;
+				w -= 3;
+			}
+
+		/* Draw the rectangle if 'tranparent station signs' is off,
+		 * or if we are drawing a general text sign (STR_2806) */
+			if (!(_display_opt & DO_TRANS_SIGNS) || ss->string == STR_2806)
+				DrawFrameRect(
+					x, y, x + w, bottom, ss->color,
+					(_display_opt & DO_TRANS_BUILDINGS) ? FR_TRANSPARENT : 0
+				);
+		}
+
+		SetDParam(0, ss->params[0]);
+		SetDParam(1, ss->params[1]);
+		/* if we didn't draw a rectangle, or if transparant building is on,
+		 * draw the text in the color the rectangle would have */
+		if ((
+					(_display_opt & DO_TRANS_BUILDINGS) ||
+					(_display_opt & DO_TRANS_SIGNS && ss->string != STR_2806)
+				) && ss->width != 0) {
+			/* Real colors need the IS_PALETTE_COLOR flag
+			 * otherwise colors from _string_colormap are assumed. */
+			colour = _colour_gradient[ss->color][6] | IS_PALETTE_COLOR;
+		} else {
+			colour = 16;
+		}
+		DrawString(
+			ss->x >> zoom, (ss->y >> zoom) - (ss->width & 0x8000 ? 2 : 0),
+			ss->string, colour
+		);
+
+		ss = ss->next;
+	} while (ss != NULL);
+}
+
+void ViewportDoDraw(const ViewPort *vp, int left, int top, int right, int bottom)
+{
+	ViewportDrawer vd;
+	int mask;
+	int x;
+	int y;
+	DrawPixelInfo *old_dpi;
+
+	byte mem[VIEWPORT_DRAW_MEM];
+	ParentSpriteToDraw *parent_list[6144];
+
+	_cur_vd = &vd;
+
+	old_dpi = _cur_dpi;
+	_cur_dpi = &vd.dpi;
+
+	vd.dpi.zoom = vp->zoom;
+	mask = (-1) << vp->zoom;
+
+	vd.combine_sprites = 0;
+
+	vd.dpi.width = (right - left) & mask;
+	vd.dpi.height = (bottom - top) & mask;
+	vd.dpi.left = left & mask;
+	vd.dpi.top = top & mask;
+	vd.dpi.pitch = old_dpi->pitch;
+
+	x = ((vd.dpi.left - (vp->virtual_left&mask)) >> vp->zoom) + vp->left;
+	y = ((vd.dpi.top - (vp->virtual_top&mask)) >> vp->zoom) + vp->top;
+
+	vd.dpi.dst_ptr = old_dpi->dst_ptr + x - old_dpi->left + (y - old_dpi->top) * old_dpi->pitch;
+
+	vd.parent_list = parent_list;
+	vd.eof_parent_list = endof(parent_list);
+	vd.spritelist_mem = mem;
+	vd.eof_spritelist_mem = endof(mem) - sizeof(LARGEST_SPRITELIST_STRUCT);
+	vd.last_string = &vd.first_string;
+	vd.first_string = NULL;
+	vd.last_tile = &vd.first_tile;
+	vd.first_tile = NULL;
+
+	ViewportAddLandscape();
+	ViewportAddVehicles(&vd.dpi);
+	DrawTextEffects(&vd.dpi);
+
+	ViewportAddTownNames(&vd.dpi);
+	ViewportAddStationNames(&vd.dpi);
+	ViewportAddSigns(&vd.dpi);
+	ViewportAddWaypoints(&vd.dpi);
+
+	// This assert should never happen (because the length of the parent_list
+	//  is checked)
+	assert(vd.parent_list <= endof(parent_list));
+
+	if (vd.first_tile != NULL) ViewportDrawTileSprites(vd.first_tile);
+
+	/* null terminate parent sprite list */
+	*vd.parent_list = NULL;
+
+	ViewportSortParentSprites(parent_list);
+	ViewportDrawParentSprites(parent_list);
+
+	if (vd.first_string != NULL) ViewportDrawStrings(&vd.dpi, vd.first_string);
+
+	_cur_dpi = old_dpi;
+}
+
+// Make sure we don't draw a too big area at a time.
+// If we do, the sprite memory will overflow.
+static void ViewportDrawChk(const ViewPort *vp, int left, int top, int right, int bottom)
+{
+	if (((bottom - top) * (right - left) << vp->zoom) > 180000) {
+		if ((bottom - top) > (right - left)) {
+			int t = (top + bottom) >> 1;
+			ViewportDrawChk(vp, left, top, right, t);
+			ViewportDrawChk(vp, left, t, right, bottom);
+		} else {
+			int t = (left + right) >> 1;
+			ViewportDrawChk(vp, left, top, t, bottom);
+			ViewportDrawChk(vp, t, top, right, bottom);
+		}
+	} else {
+		ViewportDoDraw(vp,
+			((left - vp->left) << vp->zoom) + vp->virtual_left,
+			((top - vp->top) << vp->zoom) + vp->virtual_top,
+			((right - vp->left) << vp->zoom) + vp->virtual_left,
+			((bottom - vp->top) << vp->zoom) + vp->virtual_top
+		);
+	}
+}
+
+static inline void ViewportDraw(const ViewPort *vp, int left, int top, int right, int bottom)
+{
+	if (right <= vp->left || bottom <= vp->top) return;
+
+	if (left >= vp->left + vp->width) return;
+
+	if (left < vp->left) left = vp->left;
+	if (right > vp->left + vp->width) right = vp->left + vp->width;
+
+	if (top >= vp->top + vp->height) return;
+
+	if (top < vp->top) top = vp->top;
+	if (bottom > vp->top + vp->height) bottom = vp->top + vp->height;
+
+	ViewportDrawChk(vp, left, top, right, bottom);
+}
+
+void DrawWindowViewport(const Window *w)
+{
+	DrawPixelInfo *dpi = _cur_dpi;
+
+	dpi->left += w->left;
+	dpi->top += w->top;
+
+	ViewportDraw(w->viewport, dpi->left, dpi->top, dpi->left + dpi->width, dpi->top + dpi->height);
+
+	dpi->left -= w->left;
+	dpi->top -= w->top;
+}
+
+void UpdateViewportPosition(Window *w)
+{
+	const ViewPort *vp = w->viewport;
+
+	if (WP(w, vp_d).follow_vehicle != INVALID_VEHICLE) {
+		const Vehicle* veh = GetVehicle(WP(w,vp_d).follow_vehicle);
+		Point pt = MapXYZToViewport(vp, veh->x_pos, veh->y_pos, veh->z_pos);
+
+		SetViewportPosition(w, pt.x, pt.y);
+	} else {
+		int x;
+		int y;
+		int vx;
+		int vy;
+
+		// Center of the viewport is hot spot
+		x = WP(w,vp_d).scrollpos_x + vp->virtual_width / 2;
+		y = WP(w,vp_d).scrollpos_y + vp->virtual_height / 2;
+		// Convert viewport coordinates to map coordinates
+		// Calculation is scaled by 4 to avoid rounding errors
+		vx = -x + y * 2;
+		vy =  x + y * 2;
+		// clamp to size of map
+		vx = clamp(vx, 0 * 4, MapMaxX() * TILE_SIZE * 4);
+		vy = clamp(vy, 0 * 4, MapMaxY() * TILE_SIZE * 4);
+		// Convert map coordinates to viewport coordinates
+		x = (-vx + vy) / 2;
+		y = ( vx + vy) / 4;
+		// Set position
+		WP(w, vp_d).scrollpos_x = x - vp->virtual_width / 2;
+		WP(w, vp_d).scrollpos_y = y - vp->virtual_height / 2;
+
+		SetViewportPosition(w, WP(w, vp_d).scrollpos_x, WP(w, vp_d).scrollpos_y);
+	}
+}
+
+static void MarkViewportDirty(const ViewPort *vp, int left, int top, int right, int bottom)
+{
+	right -= vp->virtual_left;
+	if (right <= 0) return;
+
+	bottom -= vp->virtual_top;
+	if (bottom <= 0) return;
+
+	left = max(0, left - vp->virtual_left);
+
+	if (left >= vp->virtual_width) return;
+
+	top = max(0, top - vp->virtual_top);
+
+	if (top >= vp->virtual_height) return;
+
+	SetDirtyBlocks(
+		(left >> vp->zoom) + vp->left,
+		(top >> vp->zoom) + vp->top,
+		(right >> vp->zoom) + vp->left,
+		(bottom >> vp->zoom) + vp->top
+	);
+}
+
+void MarkAllViewportsDirty(int left, int top, int right, int bottom)
+{
+	const ViewPort *vp = _viewports;
+	uint32 act = _active_viewports;
+	do {
+		if (act & 1) {
+			assert(vp->width != 0);
+			MarkViewportDirty(vp, left, top, right, bottom);
+		}
+	} while (vp++,act>>=1);
+}
+
+void MarkTileDirtyByTile(TileIndex tile)
+{
+	Point pt = RemapCoords(TileX(tile) * TILE_SIZE, TileY(tile) * TILE_SIZE, GetTileZ(tile));
+	MarkAllViewportsDirty(
+		pt.x - 31,
+		pt.y - 122,
+		pt.x - 31 + 67,
+		pt.y - 122 + 154
+	);
+}
+
+void MarkTileDirty(int x, int y)
+{
+	uint z = 0;
+	Point pt;
+
+	if (IS_INT_INSIDE(x, 0, MapSizeX() * TILE_SIZE) &&
+			IS_INT_INSIDE(y, 0, MapSizeY() * TILE_SIZE))
+		z = GetTileZ(TileVirtXY(x, y));
+	pt = RemapCoords(x, y, z);
+
+	MarkAllViewportsDirty(
+		pt.x - 31,
+		pt.y - 122,
+		pt.x - 31 + 67,
+		pt.y - 122 + 154
+	);
+}
+
+static void SetSelectionTilesDirty(void)
+{
+	int y_size, x_size;
+	int x = _thd.pos.x;
+	int y = _thd.pos.y;
+
+	x_size = _thd.size.x;
+	y_size = _thd.size.y;
+
+	if (_thd.outersize.x) {
+		x_size += _thd.outersize.x;
+		x += _thd.offs.x;
+		y_size += _thd.outersize.y;
+		y += _thd.offs.y;
+	}
+
+	assert(x_size > 0);
+	assert(y_size > 0);
+
+	x_size += x;
+	y_size += y;
+
+	do {
+		int y_bk = y;
+		do {
+			MarkTileDirty(x, y);
+		} while ( (y += TILE_SIZE) != y_size);
+		y = y_bk;
+	} while ( (x += TILE_SIZE) != x_size);
+}
+
+
+void SetSelectionRed(bool b)
+{
+	_thd.make_square_red = b;
+	SetSelectionTilesDirty();
+}
+
+
+static bool CheckClickOnTown(const ViewPort *vp, int x, int y)
+{
+	const Town *t;
+
+	if (!(_display_opt & DO_SHOW_TOWN_NAMES)) return false;
+
+	switch (vp->zoom) {
+		case 0:
+			x = x - vp->left + vp->virtual_left;
+			y = y - vp->top  + vp->virtual_top;
+			FOR_ALL_TOWNS(t) {
+				if (y >= t->sign.top &&
+						y < t->sign.top + 12 &&
+						x >= t->sign.left &&
+						x < t->sign.left + t->sign.width_1) {
+					ShowTownViewWindow(t->index);
+					return true;
+				}
+			}
+			break;
+
+		case 1:
+			x = (x - vp->left + 1) * 2 + vp->virtual_left;
+			y = (y - vp->top  + 1) * 2 + vp->virtual_top;
+			FOR_ALL_TOWNS(t) {
+				if (y >= t->sign.top &&
+						y < t->sign.top + 24 &&
+						x >= t->sign.left &&
+						x < t->sign.left + t->sign.width_1 * 2) {
+					ShowTownViewWindow(t->index);
+					return true;
+				}
+			}
+			break;
+
+		default:
+			x = (x - vp->left + 3) * 4 + vp->virtual_left;
+			y = (y - vp->top  + 3) * 4 + vp->virtual_top;
+			FOR_ALL_TOWNS(t) {
+				if (y >= t->sign.top &&
+						y < t->sign.top + 24 &&
+						x >= t->sign.left &&
+						x < t->sign.left + t->sign.width_2 * 4) {
+					ShowTownViewWindow(t->index);
+					return true;
+				}
+			}
+			break;
+	}
+
+	return false;
+}
+
+
+static bool CheckClickOnStation(const ViewPort *vp, int x, int y)
+{
+	const Station *st;
+
+	if (!(_display_opt & DO_SHOW_STATION_NAMES)) return false;
+
+	switch (vp->zoom) {
+		case 0:
+			x = x - vp->left + vp->virtual_left;
+			y = y - vp->top  + vp->virtual_top;
+			FOR_ALL_STATIONS(st) {
+				if (y >= st->sign.top &&
+						y < st->sign.top + 12 &&
+						x >= st->sign.left &&
+						x < st->sign.left + st->sign.width_1) {
+					ShowStationViewWindow(st->index);
+					return true;
+				}
+			}
+			break;
+
+		case 1:
+			x = (x - vp->left + 1) * 2 + vp->virtual_left;
+			y = (y - vp->top  + 1) * 2 + vp->virtual_top;
+			FOR_ALL_STATIONS(st) {
+				if (y >= st->sign.top &&
+						y < st->sign.top + 24 &&
+						x >= st->sign.left &&
+						x < st->sign.left + st->sign.width_1 * 2) {
+					ShowStationViewWindow(st->index);
+					return true;
+				}
+			}
+			break;
+
+		default:
+			x = (x - vp->left + 3) * 4 + vp->virtual_left;
+			y = (y - vp->top  + 3) * 4 + vp->virtual_top;
+			FOR_ALL_STATIONS(st) {
+				if (y >= st->sign.top &&
+						y < st->sign.top + 24 &&
+						x >= st->sign.left &&
+						x < st->sign.left + st->sign.width_2 * 4) {
+					ShowStationViewWindow(st->index);
+					return true;
+				}
+			}
+			break;
+	}
+
+	return false;
+}
+
+
+static bool CheckClickOnSign(const ViewPort *vp, int x, int y)
+{
+	const Sign *si;
+
+	if (!(_display_opt & DO_SHOW_SIGNS)) return false;
+
+	switch (vp->zoom) {
+		case 0:
+			x = x - vp->left + vp->virtual_left;
+			y = y - vp->top  + vp->virtual_top;
+			FOR_ALL_SIGNS(si) {
+				if (y >= si->sign.top &&
+						y <  si->sign.top + 12 &&
+						x >= si->sign.left &&
+						x <  si->sign.left + si->sign.width_1) {
+					ShowRenameSignWindow(si);
+					return true;
+				}
+			}
+			break;
+
+		case 1:
+			x = (x - vp->left + 1) * 2 + vp->virtual_left;
+			y = (y - vp->top  + 1) * 2 + vp->virtual_top;
+			FOR_ALL_SIGNS(si) {
+				if (y >= si->sign.top &&
+						y <  si->sign.top + 24 &&
+						x >= si->sign.left &&
+						x <  si->sign.left + si->sign.width_1 * 2) {
+					ShowRenameSignWindow(si);
+					return true;
+				}
+			}
+			break;
+
+		default:
+			x = (x - vp->left + 3) * 4 + vp->virtual_left;
+			y = (y - vp->top  + 3) * 4 + vp->virtual_top;
+			FOR_ALL_SIGNS(si) {
+				if (y >= si->sign.top &&
+						y <  si->sign.top + 24 &&
+						x >= si->sign.left &&
+						x <  si->sign.left + si->sign.width_2 * 4) {
+					ShowRenameSignWindow(si);
+					return true;
+				}
+			}
+			break;
+	}
+
+	return false;
+}
+
+
+static bool CheckClickOnWaypoint(const ViewPort *vp, int x, int y)
+{
+	const Waypoint *wp;
+
+	if (!(_display_opt & DO_WAYPOINTS)) return false;
+
+	switch (vp->zoom) {
+		case 0:
+			x = x - vp->left + vp->virtual_left;
+			y = y - vp->top  + vp->virtual_top;
+			FOR_ALL_WAYPOINTS(wp) {
+				if (y >= wp->sign.top &&
+						y < wp->sign.top + 12 &&
+						x >= wp->sign.left &&
+						x < wp->sign.left + wp->sign.width_1) {
+					ShowRenameWaypointWindow(wp);
+					return true;
+				}
+			}
+			break;
+
+		case 1:
+			x = (x - vp->left + 1) * 2 + vp->virtual_left;
+			y = (y - vp->top  + 1) * 2 + vp->virtual_top;
+			FOR_ALL_WAYPOINTS(wp) {
+				if (y >= wp->sign.top &&
+						y < wp->sign.top + 24 &&
+						x >= wp->sign.left &&
+						x < wp->sign.left + wp->sign.width_1 * 2) {
+					ShowRenameWaypointWindow(wp);
+					return true;
+				}
+			}
+			break;
+
+		default:
+			x = (x - vp->left + 3) * 4 + vp->virtual_left;
+			y = (y - vp->top  + 3) * 4 + vp->virtual_top;
+			FOR_ALL_WAYPOINTS(wp) {
+				if (y >= wp->sign.top &&
+						y < wp->sign.top + 24 &&
+						x >= wp->sign.left &&
+						x < wp->sign.left + wp->sign.width_2 * 4) {
+					ShowRenameWaypointWindow(wp);
+					return true;
+				}
+			}
+			break;
+	}
+
+	return false;
+}
+
+
+static void CheckClickOnLandscape(const ViewPort *vp, int x, int y)
+{
+	Point pt = TranslateXYToTileCoord(vp, x, y);
+
+	if (pt.x != -1) ClickTile(TileVirtXY(pt.x, pt.y));
+}
+
+
+static void SafeShowTrainViewWindow(const Vehicle* v)
+{
+	if (!IsFrontEngine(v)) v = GetFirstVehicleInChain(v);
+	ShowTrainViewWindow(v);
+}
+
+static void Nop(const Vehicle *v) {}
+
+typedef void OnVehicleClickProc(const Vehicle *v);
+static OnVehicleClickProc* const _on_vehicle_click_proc[] = {
+	SafeShowTrainViewWindow,
+	ShowRoadVehViewWindow,
+	ShowShipViewWindow,
+	ShowAircraftViewWindow,
+	Nop, // Special vehicles
+	Nop  // Disaster vehicles
+};
+
+void HandleViewportClicked(const ViewPort *vp, int x, int y)
+{
+	const Vehicle *v;
+
+	if (CheckClickOnTown(vp, x, y)) return;
+	if (CheckClickOnStation(vp, x, y)) return;
+	if (CheckClickOnSign(vp, x, y)) return;
+	if (CheckClickOnWaypoint(vp, x, y)) return;
+	CheckClickOnLandscape(vp, x, y);
+
+	v = CheckClickOnVehicle(vp, x, y);
+	if (v != NULL) {
+		DEBUG(misc, 2, "Vehicle %d (index %d) at %p", v->unitnumber, v->index, v);
+		_on_vehicle_click_proc[v->type - 0x10](v);
+	}
+}
+
+Vehicle *CheckMouseOverVehicle(void)
+{
+	const Window *w;
+	const ViewPort *vp;
+
+	int x = _cursor.pos.x;
+	int y = _cursor.pos.y;
+
+	w = FindWindowFromPt(x, y);
+	if (w == NULL) return NULL;
+
+	vp = IsPtInWindowViewport(w, x, y);
+	return (vp != NULL) ? CheckClickOnVehicle(vp, x, y) : NULL;
+}
+
+
+
+void PlaceObject(void)
+{
+	Point pt;
+	Window *w;
+
+	pt = GetTileBelowCursor();
+	if (pt.x == -1) return;
+
+	if (_thd.place_mode == VHM_POINT) {
+		pt.x += 8;
+		pt.y += 8;
+	}
+
+	_tile_fract_coords.x = pt.x & 0xF;
+	_tile_fract_coords.y = pt.y & 0xF;
+
+	w = GetCallbackWnd();
+	if (w != NULL) {
+		WindowEvent e;
+
+		e.event = WE_PLACE_OBJ;
+		e.we.place.pt = pt;
+		e.we.place.tile = TileVirtXY(pt.x, pt.y);
+		w->wndproc(w, &e);
+	}
+}
+
+
+/* scrolls the viewport in a window to a given location */
+bool ScrollWindowTo(int x , int y, Window *w)
+{
+	Point pt;
+
+	pt = MapXYZToViewport(w->viewport, x, y, GetSlopeZ(x, y));
+	WP(w, vp_d).follow_vehicle = INVALID_VEHICLE;
+
+	if (WP(w, vp_d).scrollpos_x == pt.x && WP(w, vp_d).scrollpos_y == pt.y)
+		return false;
+
+	WP(w, vp_d).scrollpos_x = pt.x;
+	WP(w, vp_d).scrollpos_y = pt.y;
+	return true;
+}
+
+
+bool ScrollMainWindowTo(int x, int y)
+{
+	Window *w;
+	bool res = ScrollWindowTo(x, y, FindWindowById(WC_MAIN_WINDOW, 0));
+
+	/* If a user scrolls to a tile (via what way what so ever) and already is on
+	 *  that tile (e.g.: pressed twice), move the smallmap to that location,
+	 *  so you directly see where you are on the smallmap. */
+
+	if (res) return res;
+
+	w = FindWindowById(WC_SMALLMAP, 0);
+	if (w == NULL) return res;
+
+	SmallMapCenterOnCurrentPos(w);
+
+	return res;
+}
+
+
+bool ScrollMainWindowToTile(TileIndex tile)
+{
+	return ScrollMainWindowTo(TileX(tile) * TILE_SIZE + TILE_SIZE / 2, TileY(tile) * TILE_SIZE + TILE_SIZE / 2);
+}
+
+void SetRedErrorSquare(TileIndex tile)
+{
+	TileIndex old;
+
+	old = _thd.redsq;
+	_thd.redsq = tile;
+
+	if (tile != old) {
+		if (tile != 0) MarkTileDirtyByTile(tile);
+		if (old  != 0) MarkTileDirtyByTile(old);
+	}
+}
+
+void SetTileSelectSize(int w, int h)
+{
+	_thd.new_size.x = w * TILE_SIZE;
+	_thd.new_size.y = h * TILE_SIZE;
+	_thd.new_outersize.x = 0;
+	_thd.new_outersize.y = 0;
+}
+
+void SetTileSelectBigSize(int ox, int oy, int sx, int sy)
+{
+	_thd.offs.x = ox * TILE_SIZE;
+	_thd.offs.y = oy * TILE_SIZE;
+	_thd.new_outersize.x = sx * TILE_SIZE;
+	_thd.new_outersize.y = sy * TILE_SIZE;
+}
+
+/* returns the best autorail highlight type from map coordinates */
+static byte GetAutorailHT(int x, int y)
+{
+	return HT_RAIL | _AutorailPiece[x & 0xF][y & 0xF];
+}
+
+// called regular to update tile highlighting in all cases
+void UpdateTileSelection(void)
+{
+	int x1;
+	int y1;
+
+	_thd.new_drawstyle = 0;
+
+	if (_thd.place_mode == VHM_SPECIAL) {
+		x1 = _thd.selend.x;
+		y1 = _thd.selend.y;
+		if (x1 != -1) {
+			int x2 = _thd.selstart.x;
+			int y2 = _thd.selstart.y;
+			x1 &= ~0xF;
+			y1 &= ~0xF;
+
+			if (x1 >= x2) intswap(x1,x2);
+			if (y1 >= y2) intswap(y1,y2);
+			_thd.new_pos.x = x1;
+			_thd.new_pos.y = y1;
+			_thd.new_size.x = x2 - x1 + TILE_SIZE;
+			_thd.new_size.y = y2 - y1 + TILE_SIZE;
+			_thd.new_drawstyle = _thd.next_drawstyle;
+		}
+	} else if (_thd.place_mode != VHM_NONE) {
+		Point pt = GetTileBelowCursor();
+		x1 = pt.x;
+		y1 = pt.y;
+		if (x1 != -1) {
+			switch (_thd.place_mode) {
+				case VHM_RECT:
+					_thd.new_drawstyle = HT_RECT;
+					break;
+				case VHM_POINT:
+					_thd.new_drawstyle = HT_POINT;
+					x1 += 8;
+					y1 += 8;
+					break;
+				case VHM_RAIL:
+					_thd.new_drawstyle = GetAutorailHT(pt.x, pt.y); // draw one highlighted tile
+			}
+			_thd.new_pos.x = x1 & ~0xF;
+			_thd.new_pos.y = y1 & ~0xF;
+		}
+	}
+
+	// redraw selection
+	if (_thd.drawstyle != _thd.new_drawstyle ||
+			_thd.pos.x != _thd.new_pos.x || _thd.pos.y != _thd.new_pos.y ||
+			_thd.size.x != _thd.new_size.x || _thd.size.y != _thd.new_size.y ||
+	    _thd.outersize.x != _thd.new_outersize.x ||
+	    _thd.outersize.y != _thd.new_outersize.y) {
+		// clear the old selection?
+		if (_thd.drawstyle) SetSelectionTilesDirty();
+
+		_thd.drawstyle = _thd.new_drawstyle;
+		_thd.pos = _thd.new_pos;
+		_thd.size = _thd.new_size;
+		_thd.outersize = _thd.new_outersize;
+		_thd.dirty = 0xff;
+
+		// draw the new selection?
+		if (_thd.new_drawstyle) SetSelectionTilesDirty();
+	}
+}
+
+// highlighting tiles while only going over them with the mouse
+void VpStartPlaceSizing(TileIndex tile, int user)
+{
+	_thd.userdata = user;
+	_thd.selend.x = TileX(tile) * TILE_SIZE;
+	_thd.selstart.x = TileX(tile) * TILE_SIZE;
+	_thd.selend.y = TileY(tile) * TILE_SIZE;
+	_thd.selstart.y = TileY(tile) * TILE_SIZE;
+	if (_thd.place_mode == VHM_RECT) {
+		_thd.place_mode = VHM_SPECIAL;
+		_thd.next_drawstyle = HT_RECT;
+	} else if (_thd.place_mode == VHM_RAIL) { // autorail one piece
+		_thd.place_mode = VHM_SPECIAL;
+		_thd.next_drawstyle = _thd.drawstyle;
+	} else {
+		_thd.place_mode = VHM_SPECIAL;
+		_thd.next_drawstyle = HT_POINT;
+	}
+	_special_mouse_mode = WSM_SIZING;
+}
+
+void VpSetPlaceSizingLimit(int limit)
+{
+	_thd.sizelimit = limit;
+}
+
+/**
+* Highlights all tiles between a set of two tiles. Used in dock and tunnel placement
+* @param from TileIndex of the first tile to highlight
+* @param to TileIndex of the last tile to highlight */
+void VpSetPresizeRange(TileIndex from, TileIndex to)
+{
+	uint distance = DistanceManhattan(from, to) + 1;
+
+	_thd.selend.x = TileX(to) * TILE_SIZE;
+	_thd.selend.y = TileY(to) * TILE_SIZE;
+	_thd.selstart.x = TileX(from) * TILE_SIZE;
+	_thd.selstart.y = TileY(from) * TILE_SIZE;
+	_thd.next_drawstyle = HT_RECT;
+
+	/* show measurement only if there is any length to speak of */
+	if (distance > 1) GuiShowTooltipsWithArgs(STR_MEASURE_LENGTH, 1, &distance);
+}
+
+static void VpStartPreSizing(void)
+{
+	_thd.selend.x = -1;
+	_special_mouse_mode = WSM_PRESIZE;
+}
+
+/* returns information about the 2x1 piece to be build.
+ * The lower bits (0-3) are the track type. */
+static byte Check2x1AutoRail(int mode)
+{
+	int fxpy = _tile_fract_coords.x + _tile_fract_coords.y;
+	int sxpy = (_thd.selend.x & 0xF) + (_thd.selend.y & 0xF);
+	int fxmy = _tile_fract_coords.x - _tile_fract_coords.y;
+	int sxmy = (_thd.selend.x & 0xF) - (_thd.selend.y & 0xF);
+
+	switch (mode) {
+	case 0: // end piece is lower right
+		if (fxpy >= 20 && sxpy <= 12) { /*SwapSelection(); DoRailroadTrack(0); */return 3; }
+		if (fxmy < -3 && sxmy > 3) {/* DoRailroadTrack(0); */return 5; }
+		return 1;
+
+	case 1:
+		if (fxmy > 3 && sxmy < -3) { /*SwapSelection(); DoRailroadTrack(0); */return 4; }
+		if (fxpy <= 12 && sxpy >= 20) { /*DoRailroadTrack(0); */return 2; }
+		return 1;
+
+	case 2:
+		if (fxmy > 3 && sxmy < -3) { /*DoRailroadTrack(3);*/ return 4; }
+		if (fxpy >= 20 && sxpy <= 12) { /*SwapSelection(); DoRailroadTrack(0); */return 3; }
+		return 0;
+
+	case 3:
+		if (fxmy < -3 && sxmy > 3) { /*SwapSelection(); DoRailroadTrack(3);*/ return 5; }
+		if (fxpy <= 12 && sxpy >= 20) { /*DoRailroadTrack(0); */return 2; }
+		return 0;
+	}
+
+	return 0; // avoids compiler warnings
+}
+
+/** Check if the direction of start and end tile should be swapped based on
+ * the dragging-style. Default directions are:
+ * in the case of a line (HT_RAIL, HT_LINE):  DIR_NE, DIR_NW, DIR_N, DIR_E
+ * in the case of a rect (HT_RECT, HT_POINT): DIR_S, DIR_E
+ * For example dragging a rectangle area from south to north should be swapped to
+ * north-south (DIR_S) to obtain the same results with less code. This is what
+ * the return value signifies.
+ * @param style HighLightStyle dragging style
+ * @param start_tile, end_tile start and end tile of drag
+ * @param boolean value which when true means start/end should be swapped */
+static bool SwapDirection(HighLightStyle style, TileIndex start_tile, TileIndex end_tile)
+{
+	uint start_x = TileX(start_tile);
+	uint start_y = TileY(start_tile);
+	uint end_x = TileX(end_tile);
+	uint end_y = TileY(end_tile);
+
+	switch (style & HT_DRAG_MASK) {
+		case HT_RAIL:
+		case HT_LINE: return (end_x > start_x || (end_x == start_x && end_y > start_y));
+
+		case HT_RECT:
+		case HT_POINT: return (end_x != start_x && end_y < start_y);
+		default: NOT_REACHED();
+	}
+
+	return false;
+}
+
+/** Calculates height difference between one tile and another
+* Multiplies the result to suit the standard given by minimap - 50 meters high
+* To correctly get the height difference we need the direction we are dragging
+* in, as well as with what kind of tool we are dragging. For example a horizontal
+* autorail tool that starts in bottom and ends at the top of a tile will need the
+* maximum of SW,S and SE,N corners respectively. This is handled by the lookup table below
+* See _tileoffs_by_dir in map.c for the direction enums if you can't figure out
+* the values yourself.
+* @param style HightlightStyle of drag. This includes direction and style (autorail, rect, etc.)
+* @param distance amount of tiles dragged, important for horizontal/vertical drags
+*        ignored for others
+* @param start_tile, end_tile start and end tile of drag operation
+* @return height difference between two tiles. Tile measurement tool utilizes
+* this value in its tooltips */
+static int CalcHeightdiff(HighLightStyle style, uint distance, TileIndex start_tile, TileIndex end_tile)
+{
+	bool swap = SwapDirection(style, start_tile, end_tile);
+	byte style_t;
+	uint h0, h1, ht; // start heigth, end height, and temp variable
+
+	if (start_tile == end_tile) return 0;
+	if (swap) swap_tile(&start_tile, &end_tile);
+
+	switch (style & HT_DRAG_MASK) {
+		case HT_RECT: {
+			static const TileIndexDiffC heightdiff_area_by_dir[] = {
+				/* Start */ {1, 0}, /* Dragging east */ {0, 0}, /* Dragging south */
+				/* End   */ {0, 1}, /* Dragging east */ {1, 1}  /* Dragging south */
+			};
+
+			/* In the case of an area we can determine whether we were dragging south or
+			 * east by checking the X-coordinates of the tiles */
+			style_t = (byte)(TileX(end_tile) > TileX(start_tile));
+			start_tile = TILE_ADD(start_tile, ToTileIndexDiff(heightdiff_area_by_dir[style_t]));
+			end_tile   = TILE_ADD(end_tile, ToTileIndexDiff(heightdiff_area_by_dir[2 + style_t]));
+		}
+		/* Fallthrough */
+		case HT_POINT:
+			h0 = TileHeight(start_tile);
+			h1 = TileHeight(end_tile);
+			break;
+		default: { /* All other types, this is mostly only line/autorail */
+			static const HighLightStyle flip_style_direction[] = {
+				HT_DIR_X, HT_DIR_Y, HT_DIR_HL, HT_DIR_HU, HT_DIR_VR, HT_DIR_VL
+			};
+			static const TileIndexDiffC heightdiff_line_by_dir[] = {
+				/* Start */ {1, 0}, {1, 1}, /* HT_DIR_X  */ {0, 1}, {1, 1}, /* HT_DIR_Y  */
+				/* Start */ {1, 0}, {0, 0}, /* HT_DIR_HU */ {1, 0}, {1, 1}, /* HT_DIR_HL */
+				/* Start */ {1, 0}, {1, 1}, /* HT_DIR_VL */ {0, 1}, {1, 1}, /* HT_DIR_VR */
+
+				/* Start */ {0, 1}, {0, 0}, /* HT_DIR_X  */ {1, 0}, {0, 0}, /* HT_DIR_Y  */
+				/* End   */ {0, 1}, {0, 0}, /* HT_DIR_HU */ {1, 1}, {0, 1}, /* HT_DIR_HL */
+				/* End   */ {1, 0}, {0, 0}, /* HT_DIR_VL */ {0, 0}, {0, 1}, /* HT_DIR_VR */
+			};
+
+			distance %= 2; // we're only interested if the distance is even or uneven
+			style &= HT_DIR_MASK;
+
+			/* To handle autorail, we do some magic to be able to use a lookup table.
+			 * Firstly if we drag the other way around, we switch start&end, and if needed
+			 * also flip the drag-position. Eg if it was on the left, and the distance is even
+			 * that means the end, which is now the start is on the right */
+			if (swap && distance == 0) style = flip_style_direction[style];
+
+			/* Use lookup table for start-tile based on HighLightStyle direction */
+			style_t = style * 2;
+			assert(style_t < lengthof(heightdiff_line_by_dir) - 13);
+			h0 = TileHeight(TILE_ADD(start_tile, ToTileIndexDiff(heightdiff_line_by_dir[style_t])));
+			ht = TileHeight(TILE_ADD(start_tile, ToTileIndexDiff(heightdiff_line_by_dir[style_t + 1])));
+			h0 = maxu(h0, ht);
+
+			/* Use lookup table for end-tile based on HighLightStyle direction
+			 * flip around side (lower/upper, left/right) based on distance */
+			if (distance == 0) style_t = flip_style_direction[style] * 2;
+			assert(style_t < lengthof(heightdiff_line_by_dir) - 13);
+			h1 = TileHeight(TILE_ADD(end_tile, ToTileIndexDiff(heightdiff_line_by_dir[12 + style_t])));
+			ht = TileHeight(TILE_ADD(end_tile, ToTileIndexDiff(heightdiff_line_by_dir[12 + style_t + 1])));
+			h1 = maxu(h1, ht);
+		} break;
+	}
+
+	if (swap) swap_uint32(&h0, &h1);
+	/* Minimap shows height in intervals of 50 meters, let's do the same */
+	return (int)(h1 - h0) * 50;
+}
+
+static const StringID measure_strings_length[] = {STR_NULL, STR_MEASURE_LENGTH, STR_MEASURE_LENGTH_HEIGHTDIFF};
+
+// while dragging
+static void CalcRaildirsDrawstyle(TileHighlightData *thd, int x, int y, int method)
+{
+	HighLightStyle b;
+	uint w, h;
+
+	int dx = thd->selstart.x - (thd->selend.x & ~0xF);
+	int dy = thd->selstart.y - (thd->selend.y & ~0xF);
+	w = myabs(dx) + 16;
+	h = myabs(dy) + 16;
+
+	if (TileVirtXY(thd->selstart.x, thd->selstart.y) == TileVirtXY(x, y)) { // check if we're only within one tile
+		if (method == VPM_RAILDIRS) {
+			b = GetAutorailHT(x, y);
+		} else { // rect for autosignals on one tile
+			b = HT_RECT;
+		}
+	} else if (h == 16) { // Is this in X direction?
+		if (dx == 16) { // 2x1 special handling
+			b = (Check2x1AutoRail(3)) | HT_LINE;
+		} else if (dx == -16) {
+			b = (Check2x1AutoRail(2)) | HT_LINE;
+		} else {
+			b = HT_LINE | HT_DIR_X;
+		}
+		y = thd->selstart.y;
+	} else if (w == 16) { // Or Y direction?
+		if (dy == 16) { // 2x1 special handling
+			b = (Check2x1AutoRail(1)) | HT_LINE;
+		} else if (dy == -16) { // 2x1 other direction
+			b = (Check2x1AutoRail(0)) | HT_LINE;
+		} else {
+			b = HT_LINE | HT_DIR_Y;
+		}
+		x = thd->selstart.x;
+	} else if (w > h * 2) { // still count as x dir?
+		b = HT_LINE | HT_DIR_X;
+		y = thd->selstart.y;
+	} else if (h > w * 2) { // still count as y dir?
+		b = HT_LINE | HT_DIR_Y;
+		x = thd->selstart.x;
+	} else { // complicated direction
+		int d = w - h;
+		thd->selend.x = thd->selend.x & ~0xF;
+		thd->selend.y = thd->selend.y & ~0xF;
+
+		// four cases.
+		if (x > thd->selstart.x) {
+			if (y > thd->selstart.y) {
+				// south
+				if (d == 0) {
+					b = (x & 0xF) > (y & 0xF) ? HT_LINE | HT_DIR_VL : HT_LINE | HT_DIR_VR;
+				} else if (d >= 0) {
+					x = thd->selstart.x + h;
+					b = HT_LINE | HT_DIR_VL;
+					// return px == py || px == py + 16;
+				} else {
+					y = thd->selstart.y + w;
+					b = HT_LINE | HT_DIR_VR;
+				} // return px == py || px == py - 16;
+			} else {
+				// west
+				if (d == 0) {
+					b = (x & 0xF) + (y & 0xF) >= 0x10 ? HT_LINE | HT_DIR_HL : HT_LINE | HT_DIR_HU;
+				} else if (d >= 0) {
+					x = thd->selstart.x + h;
+					b = HT_LINE | HT_DIR_HL;
+				} else {
+					y = thd->selstart.y - w;
+					b = HT_LINE | HT_DIR_HU;
+				}
+			}
+		} else {
+			if (y > thd->selstart.y) {
+				// east
+				if (d == 0) {
+					b = (x & 0xF) + (y & 0xF) >= 0x10 ? HT_LINE | HT_DIR_HL : HT_LINE | HT_DIR_HU;
+				} else if (d >= 0) {
+					x = thd->selstart.x - h;
+					b = HT_LINE | HT_DIR_HU;
+					// return px == -py || px == -py - 16;
+				} else {
+					y = thd->selstart.y + w;
+					b = HT_LINE | HT_DIR_HL;
+				} // return px == -py || px == -py + 16;
+			} else {
+				// north
+				if (d == 0) {
+					b = (x & 0xF) > (y & 0xF) ? HT_LINE | HT_DIR_VL : HT_LINE | HT_DIR_VR;
+				} else if (d >= 0) {
+					x = thd->selstart.x - h;
+					b = HT_LINE | HT_DIR_VR;
+					// return px == py || px == py - 16;
+				} else {
+					y = thd->selstart.y - w;
+					b = HT_LINE | HT_DIR_VL;
+				} //return px == py || px == py + 16;
+			}
+		}
+	}
+
+	if (_patches.measure_tooltip) {
+		TileIndex t0 = TileVirtXY(thd->selstart.x, thd->selstart.y);
+		TileIndex t1 = TileVirtXY(x, y);
+		uint distance = DistanceManhattan(t0, t1) + 1;
+		byte index = 0;
+		uint params[2];
+
+		if (distance != 1) {
+			int heightdiff = CalcHeightdiff(b, distance, t0, t1);
+			/* If we are showing a tooltip for horizontal or vertical drags,
+			 * 2 tiles have a length of 1. To bias towards the ceiling we add
+			 * one before division. It feels more natural to count 3 lengths as 2 */
+			if ((b & HT_DIR_MASK) != HT_DIR_X && (b & HT_DIR_MASK) != HT_DIR_Y) {
+				distance = (distance + 1) / 2;
+			}
+
+			params[index++] = distance;
+			if (heightdiff != 0) params[index++] = heightdiff;
+		}
+
+		GuiShowTooltipsWithArgs(measure_strings_length[index], index, params);
+	}
+
+	thd->selend.x = x;
+	thd->selend.y = y;
+	thd->next_drawstyle = b;
+}
+
+/**
+ * Selects tiles while dragging
+ * @param x X coordinate of end of selection
+ * @param y Y coordinate of end of selection
+ * @param method modifies the way tiles are selected. Possible
+ * methods are VPM_* in viewport.h */
+void VpSelectTilesWithMethod(int x, int y, int method)
+{
+	int sx, sy;
+	HighLightStyle style;
+
+	if (x == -1) {
+		_thd.selend.x = -1;
+		return;
+	}
+
+	/* Special handling of drag in any (8-way) direction */
+	if (method == VPM_RAILDIRS || method == VPM_SIGNALDIRS) {
+		_thd.selend.x = x;
+		_thd.selend.y = y;
+		CalcRaildirsDrawstyle(&_thd, x, y, method);
+		return;
+	}
+
+	if (_thd.next_drawstyle == HT_POINT) {
+		x += TILE_SIZE / 2;
+		y += TILE_SIZE / 2;
+	}
+
+	sx = _thd.selstart.x;
+	sy = _thd.selstart.y;
+
+	switch (method) {
+		case VPM_X_OR_Y: /* drag in X or Y direction */
+			if (myabs(sy - y) < myabs(sx - x)) {
+				y = sy;
+				style = HT_DIR_X;
+			} else {
+				x = sx;
+				style = HT_DIR_Y;
+			}
+			goto calc_heightdiff_single_direction;
+		case VPM_FIX_X: /* drag in Y direction */
+			x = sx;
+			style = HT_DIR_Y;
+			goto calc_heightdiff_single_direction;
+		case VPM_FIX_Y: /* drag in X direction */
+			y = sy;
+			style = HT_DIR_X;
+
+calc_heightdiff_single_direction:;
+			if (_patches.measure_tooltip) {
+				TileIndex t0 = TileVirtXY(sx, sy);
+				TileIndex t1 = TileVirtXY(x, y);
+				uint distance = DistanceManhattan(t0, t1) + 1;
+				byte index = 0;
+				uint params[2];
+
+				if (distance != 1) {
+					/* With current code passing a HT_LINE style to calculate the height
+					 * difference is enough. However if/when a point-tool is created
+					 * with this method, function should be called with new_style (below)
+					 * instead of HT_LINE | style case HT_POINT is handled specially
+					 * new_style := (_thd.next_drawstyle & HT_RECT) ? HT_LINE | style : _thd.next_drawstyle; */
+					int heightdiff = CalcHeightdiff(HT_LINE | style, 0, t0, t1);
+
+					params[index++] = distance;
+					if (heightdiff != 0) params[index++] = heightdiff;
+				}
+
+				GuiShowTooltipsWithArgs(measure_strings_length[index], index, params);
+			} break;
+
+		case VPM_X_AND_Y_LIMITED: { /* drag an X by Y constrained rect area */
+			int limit = (_thd.sizelimit - 1) * TILE_SIZE;
+			x = sx + clamp(x - sx, -limit, limit);
+			y = sy + clamp(y - sy, -limit, limit);
+			/* Fallthrough */
+		case VPM_X_AND_Y: /* drag an X by Y area */
+			if (_patches.measure_tooltip) {
+				static const StringID measure_strings_area[] = {
+					STR_NULL, STR_NULL, STR_MEASURE_AREA, STR_MEASURE_AREA_HEIGHTDIFF
+				};
+
+				TileIndex t0 = TileVirtXY(sx, sy);
+				TileIndex t1 = TileVirtXY(x, y);
+				uint dx = abs(TileX(t0) - TileX(t1)) + 1;
+				uint dy = abs(TileY(t0) - TileY(t1)) + 1;
+				byte index = 0;
+				uint params[3];
+
+				/* If dragging an area (eg dynamite tool) and it is actually a single
+				 * row/column, change the type to 'line' to get proper calculation for height */
+				style = _thd.next_drawstyle;
+				if (style & HT_RECT) {
+					if (dx == 1) {
+						style = HT_LINE | HT_DIR_Y;
+					} else if (dy == 1) {
+						style = HT_LINE | HT_DIR_X;
+					}
+				}
+
+				if (dx != 1 || dy != 1) {
+					int heightdiff = CalcHeightdiff(style, 0, t0, t1);
+
+					params[index++] = dx;
+					params[index++] = dy;
+					if (heightdiff != 0) params[index++] = heightdiff;
+				}
+
+				GuiShowTooltipsWithArgs(measure_strings_area[index], index, params);
+			}
+		break;
+
+		}
+		default: NOT_REACHED();
+	}
+
+	_thd.selend.x = x;
+	_thd.selend.y = y;
+}
+
+// while dragging
+bool VpHandlePlaceSizingDrag(void)
+{
+	Window *w;
+	WindowEvent e;
+
+	if (_special_mouse_mode != WSM_SIZING) return true;
+
+	e.we.place.userdata = _thd.userdata;
+
+	// stop drag mode if the window has been closed
+	w = FindWindowById(_thd.window_class,_thd.window_number);
+	if (w == NULL) {
+		ResetObjectToPlace();
+		return false;
+	}
+
+	// while dragging execute the drag procedure of the corresponding window (mostly VpSelectTilesWithMethod() )
+	if (_left_button_down) {
+		e.event = WE_PLACE_DRAG;
+		e.we.place.pt = GetTileBelowCursor();
+		w->wndproc(w, &e);
+		return false;
+	}
+
+	// mouse button released..
+	// keep the selected tool, but reset it to the original mode.
+	_special_mouse_mode = WSM_NONE;
+	if (_thd.next_drawstyle == HT_RECT) {
+		_thd.place_mode = VHM_RECT;
+	} else if ((e.we.place.userdata & 0xF) == VPM_SIGNALDIRS) { // some might call this a hack... -- Dominik
+		_thd.place_mode = VHM_RECT;
+	} else if (_thd.next_drawstyle & HT_LINE) {
+		_thd.place_mode = VHM_RAIL;
+	} else if (_thd.next_drawstyle & HT_RAIL) {
+		_thd.place_mode = VHM_RAIL;
+	} else {
+		_thd.place_mode = VHM_POINT;
+	}
+	SetTileSelectSize(1, 1);
+
+	// and call the mouseup event.
+	e.event = WE_PLACE_MOUSEUP;
+	e.we.place.pt = _thd.selend;
+	e.we.place.tile = TileVirtXY(e.we.place.pt.x, e.we.place.pt.y);
+	e.we.place.starttile = TileVirtXY(_thd.selstart.x, _thd.selstart.y);
+	w->wndproc(w, &e);
+
+	return false;
+}
+
+void SetObjectToPlaceWnd(CursorID icon, byte mode, Window *w)
+{
+	SetObjectToPlace(icon, mode, w->window_class, w->window_number);
+}
+
+#include "table/animcursors.h"
+
+void SetObjectToPlace(CursorID icon, byte mode, WindowClass window_class, WindowNumber window_num)
+{
+	Window *w;
+
+	// undo clicking on button
+	if (_thd.place_mode != 0) {
+		_thd.place_mode = 0;
+		w = FindWindowById(_thd.window_class, _thd.window_number);
+		if (w != NULL) CallWindowEventNP(w, WE_ABORT_PLACE_OBJ);
+	}
+
+	SetTileSelectSize(1, 1);
+
+	_thd.make_square_red = false;
+
+	if (mode == VHM_DRAG) { // mode 4 is for dragdropping trains in the depot window
+		mode = 0;
+		_special_mouse_mode = WSM_DRAGDROP;
+	} else {
+		_special_mouse_mode = WSM_NONE;
+	}
+
+	_thd.place_mode = mode;
+	_thd.window_class = window_class;
+	_thd.window_number = window_num;
+
+	if (mode == VHM_SPECIAL) // special tools, like tunnels or docks start with presizing mode
+		VpStartPreSizing();
+
+	if ( (int)icon < 0)
+		SetAnimatedMouseCursor(_animcursors[~icon]);
+	else
+		SetMouseCursor(icon);
+}
+
+void ResetObjectToPlace(void)
+{
+	SetObjectToPlace(SPR_CURSOR_MOUSE, VHM_NONE, 0, 0);
+}