as an addition to the toolbar (or as an alternative for users who
want to turn it off), i think shortcut keys and a right-click
menu for the figure window would be a useful addition to mpl.
some suggested shortcut keys,
(ctrl+)s = save as...
z = zoom to rectangle
p = pan (and zoom)
alt+right arrow, backspace = back
alt+left arrow = forward
esc, ctrl+w = close figure window
we already have the neat f for fullscreen.