David Lopez wrote:
> Hi, I am migrating an application from FLTK 1.1.3 to FLTK 1.1.9.
> The problem is the following
> I have a button whose callback deletes the button itself.
>
> It works fine in 1.1.3, since the code for Fl_Widget::do_callback is the
> following:
> void do_callback() {callback_(this,user_data_);}
>
> But in 1.1.9 that code changed to:
> void do_callback() {callback_(this,user_data_); if (callback_ !=
> default_callback) clear_changed();}
Yes, this was added in 1.1.5 (unfortunately).
> So, the instruction clear_changed() executes after the object was destroyed,
> causing a crash.
>
> The question is, isn't valid to delete a widget in its callback?
This has been discussed more than once, and some people (including me)
say that it ought to be possible, but it is not guranteed to work
in all cases. :-( I'm trying to improve this in FLTK 1.3, but this
is still work in progress.
> In such case, what would you suggest doing?
(1) If you can: hide the button instead of deleting it, or remove
it from the group w/o deleting it.
(2) Use FLTK 1.3 instead. This particular crash can't happen with
FLTK 1.3, because widget deletion is checked in this case.
(3) Use Fl::delete_widget() as others wrote before.
Albrecht
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