Thanks for that very easy-to-use buttons customazitation!
Here some suggestions for further improvement:
1. There are several toogle commands like "stop after current", "playback foolows cursor", "read only" (foo_utils) and so on. The buttons could also provide the information about their state if they would act like the "layout editing mode"-button wich has another background when enabled.
2. The same for commands wich are not available (f.e. main->edit->undo if no changes was made to playlist so far): These buttons could be greyed out to symbolize that they are not available.
3. [context/now playing] and [context/playlist] commands like in hotkeys configuration
4. Opportunity to add menus of the command tree as button. Example: Choose "Quick Tag" in the tree, press add, change icon - the button opens the correspondending menu when being pressed in the toolbar