Maybe it's best to provide the user with a multiple choice drop down menu, where they can choose the version. Could be added to tb-updater's _download verification screen_*.
Would it be doable to write a multiple choice feature to generic_gui_message? Or do you have any other suggestions? @troubadour
Otherwise I could try to fall back to a zenity multiple choice solution, but that would introduce another screen and would be kinda ugly.
*(Looking similar to this.)