[Lazarus] something is badly broken in GTK2, must have happened very recently

[Bernd]

Latest trunk. Linux/GTk2. It started when I noticed I could not close
certain IDE winows without causing exceptions (for example the
callstack viewer). Today I had heavy problems with lazsvnpkg's SVN
commit window, after creating a patch I could not close this window
anymore without crashing  the entire IDE. I recompiled my IDE several
times now and after a rebuild it cannot restart itself anymore (it
will crash while shutting down, I have to start the newly compiled IDE
manually again). During the attempted restart I get this message:

[...]
make: Leaving directory `/home/bernd/lazsvn/lazarus/trunk'
"IDE" completed
TMainIDE.DoRestart

***MEMORY-ERROR***: lazarus[26426]: GSlice: assertion failed:
sinfo->n_allocated > 0
Aborted
bernd at t40:~/lazsvn/lazarus/trunk\ $

The stack traces that I see do not have symbol names or line numbers,
although I have compiled the entire ide with -gl.

>From googling it seems there is something freed with g_slice_free that
was allocated with g_malloc.

Now the IDE it is crashing whenever I try to close it. And it will
also crash whenever I close a window that contains a TListView on it.
Even when it is only the design view of that form in the form
designer. Now I have loaded a project that contains some forms with
TListViews and I cannot close them or switch to another project
without crashing the IDE. Even just closing the IDE will now crash the
IDE since this project is opened with this form opened in the
designer.

Bernd