gnome-panel crashes after launching steam game (Thomas was alone)

Hello,

I encountered a minor problem on Ubuntu 13.04 with Gnome session in fallback mode. After running the game (even without launching steam application), both gnome panels (upper panel and the bottom one) disappear.

I had started gnome-panel manually in the terminal and then launched the game.

I received a following message:
(gnome-panel:3447): Gdk-ERROR **: The program 'gnome-panel' received an X Window System error.
This probably reflects a bug in the program.
The error was 'BadMatch (invalid parameter attributes)'.
  (Details: serial 32189 error_code 8 request_code 62 minor_code 0)
  (Note to programmers: normally, X errors are reported asynchronously;
   that is, you will receive the error a while after causing it.
   To debug your program, run it with the GDK_SYNCHRONIZE environment
   variable to change this behavior. You can then get a meaningful
   backtrace from your debugger if you break on the gdk_x_error() function.)

I've got currently installed gnome-panel 1:3.6.2-0ubuntu3.