Feature: Button to toggle showing advanced signal types (#9617)

src/rail_gui.cpp

@@ -1823,6 +1823,12 @@ public:
 				}
 				break;
 
+			case WID_BS_TOGGLE_SIZE:
+				_settings_client.gui.signal_gui_mode = (_settings_client.gui.signal_gui_mode == SIGNAL_GUI_ALL) ? SIGNAL_GUI_PATH : SIGNAL_GUI_ALL;
+				this->SetSignalUIMode();
+				this->ReInit();
+				break;
+
 			default: break;
 		}
 
@@ -1851,6 +1857,7 @@ static const NWidgetPart _nested_signal_builder_widgets[] = {
 	NWidget(NWID_HORIZONTAL),
 		NWidget(WWT_CLOSEBOX, COLOUR_DARK_GREEN),
 		NWidget(WWT_CAPTION, COLOUR_DARK_GREEN, WID_BS_CAPTION), SetDataTip(STR_BUILD_SIGNAL_CAPTION, STR_TOOLTIP_WINDOW_TITLE_DRAG_THIS),
+		NWidget(WWT_IMGBTN, COLOUR_DARK_GREEN, WID_BS_TOGGLE_SIZE), SetDataTip(SPR_LARGE_SMALL_WINDOW, STR_BUILD_SIGNAL_TOGGLE_ADVANCED_SIGNAL_TOOLTIP),
 	EndContainer(),
 	NWidget(NWID_VERTICAL, NC_EQUALSIZE),
 		NWidget(NWID_HORIZONTAL, NC_EQUALSIZE),