How to got `BadWindow` X error when i use GtkSocket/GtkPlug with multi-processes model?

[Andy Stewart <lazycat manatee gmail com>]

Hi all.

I'm build some multi-processes framework with GtkSocekt/GtkPlug,
GtkSocekt running in main process, Every GtkPlug running in separate
processes.

But when i running my program, i got below X window error:
------------------------------> X error start <------------------------------
(Manatee:12122): Gdk-WARNING **: GdkWindow 0x4200003 unexpectedly destroyed
The program 'Manatee' received an X Window System error.
This probably reflects a bug in the program.
The error was 'BadWindow (invalid Window parameter)'.
  (Details: serial 191 error_code 3 request_code 18 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.)
------------------------------> X error end   <------------------------------

And this error not always occur, sometimes my program running well.
I guess X windows changes when GtkPlug plug-in GtkSocekt then got above
error, but i'm not sure.

I want some hint to fix my problem, so i want to know: 

When time get `BadWindow` error? 

GtkSocekt/GtkPlug will be a cause?


Thanks for your help!

  -- Andy