Comment 6 for bug 93914

I had the same problem on Ubuntu 7.10 (fresh install) and tilda 0.09.4-4:

$ tilda

(tilda:10582): Gdk-CRITICAL **: gdk_window_set_geometry_hints: assertion `GDK_IS_WINDOW (window)' failed
The program 'tilda' received an X Window System error.
This probably reflects a bug in the program.
The error was 'BadAccess (attempt to access private resource denied)'.
  (Details: serial 11 error_code 10 request_code 33 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 --sync command line
   option to change this behavior. You can then get a meaningful
   backtrace from your debugger if you break on the gdk_x_error() function.)

Then I launched tilda as root using 'gksudo tilda' and it started properly but I couldn't use the default keybinding (NONE+F1) to launch it. So this made me think the problem was caused because I had the F1 key customized in "System -> Preferences -> Keyboard Shorcuts".

The solution is to change the tilda key binding on ~/.tilda/config_0 or to remove the custom key binding in Gnome settings that uses the same key binding as tilda.

Hope this helps. Let me know if you need more testing to reproduce the bug.