Steps to reproduce:
1. Load a big file into sources, then drag it to the column below and fast forward the movie
2. 
3. 


Stack trace:
http://paste.ubuntu-nl.org/30016/

ralph@ralph:~$ pitivi
The program 'pitivi' received an X Window System error.
This probably reflects a bug in the program.
The error was 'BadAlloc (insufficient resources for operation)'.
  (Details: serial 75303 error_code 11 request_code 53 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.)


Other information: