Do not show signal window toggle size button in realistic braking mode

src/rail_gui.cpp

@@ -1847,6 +1847,9 @@ private:
 				WID_BS_ELECTRIC_EXIT, WID_BS_SEMAPHORE_COMBO, WID_BS_ELECTRIC_COMBO, WIDGET_LIST_END);
 		this->SetWidgetsDisabledState(!show_progsig, WID_BS_SEMAPHORE_PROG, WID_BS_ELECTRIC_PROG, WIDGET_LIST_END);
 		this->SetWidgetsDisabledState(!this->noentry_ui_shown, WID_BS_SEMAPHORE_NO_ENTRY, WID_BS_ELECTRIC_NO_ENTRY, WIDGET_LIST_END);
+
+		this->GetWidget<NWidgetStacked>(WID_BS_TOGGLE_SIZE_SEL)->SetDisplayedPlane(!this->realistic_braking_mode ? 0 : SZSP_NONE);
+		this->SetWidgetDisabledState(WID_BS_TOGGLE_SIZE, this->realistic_braking_mode);
 	}
 
 	void ClearRemoveState()
@@ -2081,7 +2084,9 @@ 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),
+		NWidget(NWID_SELECTION, INVALID_COLOUR, WID_BS_TOGGLE_SIZE_SEL),
+			NWidget(WWT_IMGBTN, COLOUR_DARK_GREEN, WID_BS_TOGGLE_SIZE), SetDataTip(SPR_LARGE_SMALL_WINDOW, STR_BUILD_SIGNAL_TOGGLE_ADVANCED_SIGNAL_TOOLTIP),
+		EndContainer(),
 	EndContainer(),
 	NWidget(NWID_VERTICAL, NC_EQUALSIZE),
 		NWidget(NWID_HORIZONTAL, NC_EQUALSIZE),

src/widgets/rail_widget.h

@@ -103,6 +103,7 @@ enum BuildSignalWidgets {
 	WID_BS_DRAG_SIGNALS_DENSITY_LABEL,    ///< The current signal density.
 	WID_BS_DRAG_SIGNALS_DENSITY_DECREASE, ///< Decrease the signal density.
 	WID_BS_DRAG_SIGNALS_DENSITY_INCREASE, ///< Increase the signal density.
+	WID_BS_TOGGLE_SIZE_SEL,     ///< NWID_SELECTION for WID_BS_TOGGLE_SIZE
 	WID_BS_SEMAPHORE_NORM_SEL,  ///< NWID_SELECTION for WID_BS_SEMAPHORE_NORM
 	WID_BS_ELECTRIC_NORM_SEL,   ///< NWID_SELECTION for WID_BS_ELECTRIC_NORM
 	WID_BS_SEMAPHORE_ENTRY_SEL, ///< NWID_SELECTION for WID_BS_SEMAPHORE_ENTRY