One more comment: X/Compiz work fine on the LCD-only configuration. The 800x600 rectangle the cursor is confined to in the double-headed config is notable because it's the same resolution that the GDM takes (probably because it's the largest VESA-like mode both monitors can show).
One more comment: X/Compiz work fine on the LCD-only configuration. The 800x600 rectangle the cursor is confined to in the double-headed config is notable because it's the same resolution that the GDM takes (probably because it's the largest VESA-like mode both monitors can show).