I discovered a display bug in the button control when used with an icon and/or a menu after importing some symbols I’d made in B2. For the icon, it does not always appear where I’d expect, especially when the width of the button gets “too small”. For the menu, if there is no text in the button label, the menu caret positions itself at the very right side of the button rather than in by the roughly five pixels it should be. Adding a single character puts it where it should be. So to just get a single icon with a menu you have to insert a space character as a button label, but that has the side effect of changing the position of the icon just slightly to the left. (See image at the bottom).
I’m not exactly sure what to do in the “width too small” cases (short of forcing the button to a minimum width based on the presence or absence of icons and menu carets). However, being able to show just an icon and a menu caret with no need for a space character should definitely be possible.