Dragging file into Quick Designer does nothing

1. Open a .qml file.
2. Go to Design mode.
3. Drag a file from a file manager over to the canvas.
   You'll see an icon with a "+" indicating that Creator will accept dropping this file.
4. Drop the file.
   Nothing happens.

Creator should do one of the following:

• Open the file
• Insert the file's content as an Item into the open file
• Show an icon that it will not accept dropping the file