In the buttons window's "Panel" menu, there is a "View
All" item which has the hotkey "Home".
It actually resizes the panels so that they are as
large as possible, vertically. It seems to totally
ignore the width of the buttons window. So sometimes
when "View All" is used, a lot of the panels are cut
off. e.g. try starting with the blender default file
and increase the height of the buttons window
(simultaneously reducing the height of the 3d window) -
then go to "View All" or "Home"...

I think either the menu item needs to be renamed (Fit
Height or something) or it needs to take the buttons
window's width and height into account so that the
panels are as large as possible, but are all visible.