Disable Gnome panels on secondary X screen

[nasevz]

I have both monitor and TV connected to my computer. I use TV for XBMC and Mythtv and it is configured as separate X screen. When I start Mythtv on a TV, Top and bottom Gnome pannels are visible. I can disable them, but it lasts only one session and after reboot they are back again. I would like panels on my primary screen on the monitor to stay enabled and no panels on secondary screen.
Any suggestions how to do that?