Fix: Apply widget's internal padding to scrollbar capacity/position. (#12801)

For non-WWT_MATRIX widgets, scrollbars need to take account of the internal padding used for the widget.

This is not normally noticeable as framerect padding is only 2 extra pixels

src/order_gui.cpp

@@ -1586,7 +1586,7 @@ public:
 	void OnResize() override
 	{
 		/* Update the scroll bar */
-		this->vscroll->SetCapacityFromWidget(this, WID_O_ORDER_LIST);
+		this->vscroll->SetCapacityFromWidget(this, WID_O_ORDER_LIST, WidgetDimensions::scaled.framerect.Vertical());
 	}
 
 	static inline HotkeyList hotkeys{"order", {