Steps to reproduce:

• create/open Qt Quick UI / Application using Quick Controls
• switch to Designer
• Navigator lists toolBar and statusBar as properties of the ApplicationWindow
• drag a ToolBar and a StatusBar onto the preview (both just get added to the ApplicationWindow as 'normal' childs)
• inside the Navigator try to drag the ToolBar onto the toolBar property (or StatusBar onto the statusBar property)
  • this is not possible
• switch to Edit mode
• add a toolBar property and cut'n'paste the ToolBar item to this property, do the same with statusBar
• switch back to Design mode
  • Navigator now displays correctly ToolBar as child of the toolBar property and StatusBar as child of statusBar property