Add optional background color to all sources/ annotations
Please add the ability to draw a background box under all sources/ annotations. The ones specifically desired are Text and Annotate Time.
Reason for this request: There are times a user zooms into her data, and shows only her data. If the color map has a lot of black in it (such as a black body radiation color map), black text (from a white background palette) will not be visible.
@utkarsh.ayachit @cory.quammen Should we make this 5.7, or 5.8?