Two questions about making the PopupGalleryTool look nice.

1. In the screenshot you see a PopupGalleryTool with a gray line at the bottom, marked in pink. It may be a left-over of the ResizeDropDown. How can I get rid of the gray line and the space it occupies?

2.There is empty white space to the right of the items, marked in red. How can I get rid of that space?

I've been searching for answers to these question without success. Even if the answers were in the forum, I have a hard time coming up with the proper search terms. What is the strategy for finding answers to such questions?

TIA!
Hans