Gtk2: Stopping a search in FIF4 crashes the program

[LouieTian0209]

Version: Linux gtk2

Steps to reproduce:

1. Launch FIF4 window
2. Perform some search on a directory
3. While the searching is still going on, click on the "X" from the title bar
4. Confirm you would like to stop the search
5. The program crashes

Error log:

The program 'cudatext' received an X Window System error.
This probably reflects a bug in the program.
The error was 'BadWindow (invalid Window parameter)'.
  (Details: serial 59909 error_code 3 request_code 12 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.)

I also tried with qt5 version and didn't have this issue. However, it's not steadily reproducible as I tried the same action on gtk2 version a few times and only got it happen once.

[Alexey-T]

What if you stop the search by pressing ESC (and confirming to stop)?

[LouieTian0209]

Tried several times with both stopping by ESC and by clicking X. Did not trigger the crash at all.

I'll try more later.

[Alexey-T]

I read in this month that Lazarus has fixes for modal dialog crashes in gtk2. I don't know is that connected this our crash. maybe. next Cud will use last Lazarus (from git) so you will see.