-ContextMenuActionProvider *GraphicalUi::_contextMenuActionProvider = 0;
-ToolBarActionProvider *GraphicalUi::_toolBarActionProvider = 0;
-UiStyle *GraphicalUi::_uiStyle = 0;
+ContextMenuActionProvider *GraphicalUi::_contextMenuActionProvider = nullptr;
+ToolBarActionProvider *GraphicalUi::_toolBarActionProvider = nullptr;
+UiStyle *GraphicalUi::_uiStyle = nullptr;