1) When I use buttons, there is a noticeable (and mildly annoying) text redrawing every time file status changes from changed to unchanged or vice versa. That is, every time the asterisk is added or removed to the file name in the button. This does not happen when I use tabs. The buttons use a custom font which is bigger than the font on tabs (that's why I have a slight preference for buttons). I don't detect any change in the button height when the asterisk appears or any other change in widgets geometry, so this redrawing is probably unnecessary.

2) Right click tabs/buttons bar to bring up context menu -> Customize Tab -> Tab -> change style from tab to button or from button to tab. Right click tab/button toolbar again. 'Find Toolbar' and 'HTML Toolbar' both became 'Toolbar'.