Editor: Do not allow elements to replace photos in image frames

Many schools fill up the entire canves with photos leaving "0" blank space. The issue now is that if you try to add a clip-art element, it replaces an image rather than applying the clip-art over the image.  Is this caused by a bug to have clip-art replace images?  

Or a fix would be to have the option to "Apply to page" once you hoover over a clip-art element to replacing of image.