This is something weird about GNOME Flashback. Though to be fair, I do recall
the menus being really finnicky in GNOME 2, so I can see why they did it. (I
remember having a lot of difficulty in GNOME 2 getting the menus for the
right things, or something to that effect.)
Personally, I prefer GNOME Shell (the default GNOME interface), but Ruben has
chosen GNOME Flashback for performance and I guess a bit of traditionalism.
Though judging from your complaints, you might dislike GNOME Shell even more
than GNOME Flashback. Perhaps KDE would be better for you. (It wouldn't be a
great choice as a default for Trisquel, however, given how heavy it is.)
If you do want to try KDE, you could try the "triskel" package, or there's
the "kde-plasma-desktop" package.
