Re: Non modal dialog : how?

[Kjell Ahlstedt <kjell ahlstedt bredband net>]

(When I sent this email yesterday, it could not be delivered to 
gtkmm-list due to some unavailable server. I try again now.)

Gtk::Widget::show() is asynchronous, i.e. it returns before the widget 
is fully shown. During sleep() or any other long operation after show(), 
events in the main event loop are not processed. You can use show_now() 
instead of show(), but that will only partly solve your problem. The 
message dialog is fully shown when the call to show_now() returns, but 
your program's GUI does not respond during sleep() or another long 
operation. E.g. if one of your windows is covered by another window, and 
then uncovered, it will not redraw itself immediately.

You can mitigate the problem by running the main loop now and then. I 
tested with the following code

    m_MessageDialog_Modeless->show_now();
    for (int i = 0; i < 10; i++)
    {
      sleep(1);
      // Dispatch all events in the main event queue, if any.
      while (Glib::MainContext::get_default()->iteration(false))
        ;
    }

where sleep(1) is meant to simulate your long operation, divided into 
shorter parts.

This solution is fairly easy to implement, but it's not the best one, 
and it may have strange side-effects. A program with long-running 
operations works best, if it contains several threads. Two threads are 
usually enough. One thread handles the GUI and other user interactions. 
Another thread, with lower priority, runs the long operations.

Kjell


2013-05-13 16:53, Yannick Barbeaux skrev:
> Thank you for your help.
> I have found out where the problem comes from (but no solution yet) : the
> point is that I want the modeless dialog to be closed automatically after
> running a given operation.
> To simulate this behaviour in your code Kjell, I just added a sleep() call
> right after the show method (then I delete the dialog after sleeping). In
> your function "on_button_modeless_clicked()" :
>
> [...]
> m_MessageDialog_Modeless->show();
> sleep(4);
> delete m_MessageDialog_Modeless;
> m_MessageDialog_Modeless = 0;
>
>
> Note that if I do anything else than sleep (any long operation), I have the
> same behaviour : the window appears all blank (no widget).
>
> If I just let the sleep line (and do not delete the dialog after), the
> dialog appears blank during 4 seconds (sleep time) then the wigets (labels)
> appear.
>
> My observation is that the dialog does not appear correctly before exiting
> the event handler. Correct? Could anyone confirm and explain why?