Bug#605401: d-i window does not account for GNOME pannels and window decoration
There is a workaround for this (GNOME-specific, but may have counterparts for
other flavours). Bring up the GNOME keyboard shortcuts configuration:
System -> Preferences -> Keyboard Shortcuts
Scroll down and under "Window Management", select "Toggle fullscreen mode"
which is disabled by default. Press F11, which is the usual shortcut.
Now start the launcher and press F11. The decorations will be removed and
the window will cover the panels, so the disappearing buttons problem is
It would be better if d-i run in GTK mode would force fullscreen instead of
just assuming it is set.