# HG changeset patch
# Parent 2415d464b5bacd2193242b911e474841781da0f4

diff -r 2415d464b5ba src/rail_gui.cpp
--- a/src/rail_gui.cpp	Thu Sep 05 13:28:29 2013 +0200
+++ b/src/rail_gui.cpp	Thu Sep 05 13:28:57 2013 +0200
@@ -1452,6 +1452,8 @@
 
 struct BuildSignalWindow : public PickerWindowBase {
 private:
+	Dimension sig_sprite_size;
+
 	/**
 	 * Draw dynamic a signal-sprite in a button in the signal GUI
 	 * Draw the sprite +1px to the right and down if the button is lowered
@@ -1504,6 +1506,31 @@
 		}
 	}
 
+	virtual void OnInit()
+	{
+		/* Calculate maximum signal sprite size. */
+		this->sig_sprite_size.width = 0;
+		this->sig_sprite_size.height = 0;
+		const RailtypeInfo *rti = GetRailTypeInfo(_cur_railtype);
+		for (uint type = SIGTYPE_NORMAL; type < SIGTYPE_END; type++) {
+			for (uint variant = SIG_ELECTRIC; variant <= SIG_SEMAPHORE; variant++) {
+				for (uint lowered = 0; lowered < 2; lowered++) {
+					const Sprite *sprite = GetSprite(rti->gui_sprites.signals[type][variant][lowered], ST_NORMAL);
+					this->sig_sprite_size.width = max<int>(this->sig_sprite_size.width, UnScaleByZoom(sprite->width, ZOOM_LVL_GUI));
+					this->sig_sprite_size.height = max<int>(this->sig_sprite_size.height, UnScaleByZoom(sprite->height, ZOOM_LVL_GUI));
+				}
+			}
+		}
+	}
+
+	virtual void UpdateWidgetSize(int widget, Dimension *size, const Dimension &padding, Dimension *fill, Dimension *resize)
+	{
+		if (IsInsideMM(widget, WID_BS_SEMAPHORE_NORM, WID_BS_ELECTRIC_PBS_OWAY + 1)) {
+			size->width = max(size->width, this->sig_sprite_size.width + padding.width + WD_IMGBTN_LEFT + WD_IMGBTN_RIGHT);
+			size->height = max(size->height, this->sig_sprite_size.height + padding.height + WD_IMGBTN_TOP + WD_IMGBTN_BOTTOM);
+		}
+	}
+
 	virtual void DrawWidget(const Rect &r, int widget) const
 	{
 		if (IsInsideMM(widget, WID_BS_SEMAPHORE_NORM, WID_BS_ELECTRIC_PBS_OWAY + 1)) {