#2 "Back to FF/TB"-button slides off window

[Asciimonster]

This problems affects the windows where a menu
structure is shown on the left, such as the extension
pages of FF and TB. At the bottom of this menu page
there is a back button.

If a translation of one or more of the menu items is
longer than 1 line, the back button moves down. In the
worst case, it moves off the window.

Could somebody fix the back button at the left bottom
side if the window? Please allow for two lines of text
in the back button.