Make it so that you can have Filled and Masking Regions on both Title and 3D Views. I don't know why you stop me from being able to use a filled region on something like my Sheets, were I might want them to use graphically for various elements.
Additionally, often I might get a 3d View setup just right, and then I want to clean up some things with a Filled Region, or Masking Region. Most often I want to use it to hide elements that I only want partially exposed in the view. But you won't let me do it. Frankly, it's low hanging fruit and something you should easily be adding.
