I would like to be able to add a “speech bubble” or “caption” that is square with optional border (and a color picker for the border line) plus an option for no fill or fill of a given color (color picker).
One option might be to simply provide a square speech bubble.
In the overlay tool, in some places where there are color choices, a color picker is used that allows extensive options, but in other places only a couple of colors are available. It would be great to have the color picker available in all places where there are color options.