The toolbar directly above the message window in Thunderbird's Write window has has one large button with all the icons on it (some of them duplicated in each of two rows) and many small buttons right next to it, one for each icon [see attached screenshot]. It has been that way through several updates now. What is going on? (When I click on the screwed-up button, I get a drop-down menu for font sizes - tiny, small, medium, etc.)