800 x 480 = dialogue buttons off screen

[Adam]

Im running up a touchscreen PC, and finding that the window manager is
not resizing dialogue windows vertically to fit the screen correctly.
The window hides behind the panel and taskbar as well, so its not
respecting their borders or the screen border. Horizontally the window
resizing works as expected.

Is 480 too small for xfce or is there some way i can fix this?