flash plugins are crashing mozilla and firefox on RELENG_5

[Andreas Wacknitz]

Both mozilla and firefox are crashing with installed native flash plugins
(www/flashplugin-mozilla, www/flashplugin-firefox) when leaving a page that
contains a flash animation:

firefox-bin in free(): warning: chunk is already free
The program 'firefox-bin' received an X Window System error.
This probably reflects a bug in the program.
The error was 'BadShmSeg (invalid shared segment parameter)'.
  (Details: serial 233 error_code 170 request_code 146 minor_code 2)
  (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.)

Will this be fixed before 5.3?

If it matters: x window system is xorg.

Best regards
Andreas