Well, my overscan is a bit more off the screen... i can *guess* at where to find the drop-downs in the menu bar on gnome (top bar on mine), and the alt-tab can flip through the windows fine, but the Myth setup menus have check-boxes that are off the side (left) and I'd have to resize the desktop to see them (i.e. I have no idea if the openGL is enabled until i resize it). The Myth setting to resize/shift the TV output only applies to the actual TV signal, not the menus that must run in full screen.
But it would be nice for all applications if the screen size fit my viewable screen... I tried to resize the display in the 'service mode' on the TV, but the convergence is so messed up past the edges I don't want to bring it in any more.