[Cc: to the Debian Bug Tracking System]
* Paul Boersma <[EMAIL PROTECTED]> [2005-06-15 17:40]:
> of course we don't know that the error is in lesstif or whether instead
> Motif is more lenient. The error message is just the one you sent me:
>
> > Warning: XtRemoveGrab asked to remove a widget not on the list
> > Warning: XtRemoveGrab asked to remove a widget not on the list
> > Warning: XtRemoveGrab asked to remove a widget not on the list
> > X Error of failed request: BadWindow (invalid Window parameter)
> > Major opcode of failed request: 10 (X_UnmapWindow)
> > Resource id in failed request: 0x0
> > Serial number of failed request: 8394
> > Current serial number in output stream: 8400
>
> The first three are just ominous warnings of something that is about to
> go wrong later on. Neither the warnings nor the error message occurs
> with Motif. That the error is in X_UnmapWindow means that X11 is given
> the order to make a window invisible that has already been destroyed.
> The warning about XtRemoveGrab is similar: ownership of the mouse is
> removed from a window that lesstif thinks has the ownership but in
> reality has already been destroyed.
>
> It may be a timing problem. Praat first says: "make this window
> invisible", then "destroy this window". If these commands are executed
> in the order they are given, there will be no problem. If, however, the
> first command is delayed till after the window has been destroyed,
> there will be a crash. The question, then, is whether the programmer is
> allowed to rely on a synchronous behaviour of these two commands.
Thanks for the additional information, Paul.
I noticed that the bug occurs only in a quite specific situation, namely
after the file selection widget is called for opening/saving scripts.
If you do just this:
[main window] Control -> New Praat script
[script window] File -> Close
then there is no crash. However, if you do either:
[main window] Control -> Open Praat script...
[file selection window] Cancel
[script window] File -> Close
or
[main window] Control -> New Praat script
[script window] File -> Open
[file selection window] Cancel
[script window] File -> Close
then there is a crash.
It seems that opening and closing the file selection widget introduce
some memory manipulation problem, which manifests itself when the
script window is closed. Motif seems to be insensible to the problem,
while Lesstif isn't, unless it is a genuine Lesstif bug.
--
Rafael
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