This is a small issue and it might just be my issue with a rouge style somewhere.
If I add a 'RadRibbonDropDownButton', that has a RadGlyph as it's image then letters with descenders like 'g' and 'j' get their tails cropped ever so slightly.
It doesn't happen with the 'RadRibbonSplitButton' and I have not tired other themes. It's a very minor issue but it does catch the eye when you are reading buttons on the ribbon.
Screenshots attached of the issue and zoomed in 400% , notice the tails j and g's of the dropdown button on the right.