Gui: add convenience functions to SelectionFilterGate

src/Mod/Part/Gui/TaskShapeBuilder.cpp

@@ -62,7 +62,7 @@ namespace PartGui {
         enum Type {VERTEX, EDGE, FACE, ALL};
         Type mode;
         ShapeSelection()
-            : Gui::SelectionFilterGate((Gui::SelectionFilter*)nullptr), mode(ALL)
+            : Gui::SelectionFilterGate(nullPointer()), mode(ALL)
         {
         }
         void setMode(Type mode)
@@ -172,7 +172,7 @@ void ShapeBuilderWidget::on_createButton_clicked()
 {
     int mode = d->bg.checkedId();
     Gui::Document* doc = Gui::Application::Instance->activeDocument();
-    if (!doc)
+    if (!doc)
         return;
 
     try {