[Gambas-user] Experiencing a "flicker" when "show"ing a form ...

[Benoît Minisini]

Le 14/10/2012 17:12, Gerry Douglas a écrit :
> Benoît,
>
> Thanks you for working on this.  So to build a db.gkt applications I select
> GTK+ application when creating the project?  I tried this, but I still see
> the flicker.  Would you have time to send me a sample project where there
> is no flicker for me to try on my computer?
>
> Regards<
> Gerry.
>

I didn't succeed in removing the flicker. I don't understand why there 
is a flicker at all, and I didn't notice it with gb.gtk, or when I 
disable the desktop composition in KDE.

I actually don't know, when you show a window and hide another one, if 
we have the guarantee that this is done in the same order.

I don't have the flicker with desktop composition disabled, but I see a 
blink. So I think that with desktop composition enabled, you see the 
background during the flicker, because the compositor has cached it, 
whereas with no composition, there is no cache, and the background does 
not have the time to redraw itself because the second fullscreen window 
appears.

In other words, we have the following sequences:

Desktop composition enabled:

1) The first fullscreen window is hidden.
2) The background is redrawn (-> flicker).
3) The second fullscreen window is shown.

Desktop composition disabled:

1) The first fullscreen window is hidden.
2) The background is asked to be redrawn but does not have the time to 
do it (-> just a little blink).
3) The second fullscreen window is shown.

And exchanging the Show/Hide calls in the Gambas code seems to change 
nothing! Not logical, is it?

-- 
Benoît Minisini