Index: src/rail_gui.cpp
===================================================================
--- src/rail_gui.cpp	(revision 17206)
+++ src/rail_gui.cpp	(working copy)
@@ -314,7 +314,7 @@
 
 /** Updates the Remove button because of Ctrl state change
  * @param w window the button belongs to
- * @return true iff the remove buton was changed
+ * @return true if the remove button was changed
  */
 static bool RailToolbar_CtrlChanged(Window *w)
 {
@@ -548,7 +548,7 @@
 		return;
 	}
 
-	const Window *w = FindWindowById(WC_BUILD_SIGNAL, 0);
+	Window *w = FindWindowById(WC_BUILD_SIGNAL, 0);
 
 	if (w != NULL) {
 		/* signal GUI is used */
@@ -575,6 +575,11 @@
 			CMD_REMOVE_SIGNAL_TRACK | CMD_MSG(STR_ERROR_CAN_T_REMOVE_SIGNALS_FROM) :
 			CMD_BUILD_SIGNAL_TRACK  | CMD_MSG(STR_ERROR_CAN_T_BUILD_SIGNALS_HERE),
 		CcPlaySound1E);
+	if (_ctrl_pressed) {
+		/* _thd hasn't been reset yet, so do it manually to let OnCTRLStateChange() switch to alternate variant */
+		 _thd.size.x = _thd.size.y = TILE_SIZE;
+		w->OnCTRLStateChange(); // Default variant was shown during ctrl-drag. Restore alternate variant on mouse-up
+	}
 }
 
 
@@ -725,9 +730,14 @@
 
 	virtual void OnPlaceDrag(ViewportPlaceMethod select_method, ViewportDragDropSelectionProcess select_proc, Point pt)
 	{
-		/* no dragging if you have pressed the convert button */
-		if (FindWindowById(WC_BUILD_SIGNAL, 0) != NULL && _convert_signal_button && this->IsWidgetLowered(RTW_BUILD_SIGNALS)) return;
+		Window *w = FindWindowById(WC_BUILD_SIGNAL, 0);
 
+		if (w != NULL) {
+			/* No dragging if you have pressed the convert button */
+			if (_convert_signal_button && this->IsWidgetLowered(RTW_BUILD_SIGNALS)) return;
+
+			w->OnCTRLStateChange();
+		}
 		VpSelectTilesWithMethod(pt.x, pt.y, select_method);
 	}
 
@@ -1536,7 +1546,10 @@
 
 	virtual void OnPaint()
 	{
-		this->LowerWidget((_cur_signal_variant == SIG_ELECTRIC ? BSW_ELECTRIC_NORM : BSW_SEMAPHORE_NORM) + _cur_signal_type);
+		/* There's no need do raise and lower widgets on each paint cycle if one is already lowered */
+		if (!this->IsWidgetLowered(BSW_ELECTRIC_NORM + _cur_signal_type) && !this->IsWidgetLowered(BSW_SEMAPHORE_NORM + _cur_signal_type)) {
+			this->OnCTRLStateChange();
+		}
 
 		this->SetWidgetLoweredState(BSW_CONVERT, _convert_signal_button);
 
@@ -1581,7 +1594,7 @@
 			case BSW_ELECTRIC_COMBO:
 			case BSW_ELECTRIC_PBS:
 			case BSW_ELECTRIC_PBS_OWAY:
-				this->RaiseWidget((_cur_signal_variant == SIG_ELECTRIC ? BSW_ELECTRIC_NORM : BSW_SEMAPHORE_NORM) + _cur_signal_type);
+				this->RaiseWidget((this->IsWidgetLowered(BSW_ELECTRIC_NORM + _cur_signal_type) ? BSW_ELECTRIC_NORM : BSW_SEMAPHORE_NORM) + _cur_signal_type);
 
 				_cur_signal_type = (SignalType)((uint)((widget - BSW_SEMAPHORE_NORM) % (SIGTYPE_LAST + 1)));
 				_cur_signal_variant = widget >= BSW_ELECTRIC_NORM ? SIG_ELECTRIC : SIG_SEMAPHORE;
@@ -1589,6 +1602,11 @@
 
 			case BSW_CONVERT:
 				_convert_signal_button = !_convert_signal_button;
+				if (_convert_signal_button && _ctrl_pressed) {
+					/* Hide signal type button if convert is pressed while ctrl is held */
+					this->RaiseWidget((this->IsWidgetLowered(BSW_ELECTRIC_NORM + _cur_signal_type)
+						? BSW_ELECTRIC_NORM : BSW_SEMAPHORE_NORM) + _cur_signal_type);
+				}
 				break;
 
 			case BSW_DRAG_SIGNALS_DENSITY_DECREASE:
@@ -1610,6 +1628,22 @@
 
 		this->SetDirty();
 	}
+
+	virtual EventState OnCTRLStateChange()
+	{
+		this->RaiseWidget((this->IsWidgetLowered(BSW_ELECTRIC_NORM + _cur_signal_type) ? BSW_ELECTRIC_NORM : BSW_SEMAPHORE_NORM) + _cur_signal_type);
+		/* Only switch variant buttons with ctrl if not currently dragging (more than 1 tile highlighted) */
+		if (_ctrl_pressed && _thd.size.x == TILE_SIZE && _thd.size.y == TILE_SIZE) {
+			/* Using the signal converter with ctrl doesn't depend on selected signal,
+			 * so it's clearer to leave buttons raised for the duration of ctrl-press. */
+			if (!_convert_signal_button) this->LowerWidget(((_cur_signal_variant == SIG_ELECTRIC) ? BSW_SEMAPHORE_NORM : BSW_ELECTRIC_NORM) + _cur_signal_type);
+		} else {
+			/* Lower default button widget (the one that was actually pressed) */
+			this->LowerWidget(((_cur_signal_variant == SIG_ELECTRIC) ? BSW_ELECTRIC_NORM : BSW_SEMAPHORE_NORM) + _cur_signal_type);
+		}
+		this->SetDirty();
+		return ES_NOT_HANDLED;
+	}
 };
 
 /** Nested widget definition of the build signal window */