QMdiArea unwanted actvation

I'm using a QMdiArea as the central widget of my application and one of its subwindow itself contains another QMdiArea. As long as I keep my application on top of others everything *looks* fine but when I switch to another window and switch back to my app I face the weirdest (and among the most annoying) issue I've ever faced in Qt : QMdiArea automatically changes the active subwindow to the one owning another QMdiArea... I've any sort of software lock (signals based) I could think of, even tried to force the QMdiArea to set back the previous subwindow by keeping track of it but it just does not work...
I read the docs again and again and found no clues... Just to make sure the problem does not come from my code I checked another app using the same QMdiArea nesting and was able to reproduce the bug... Does anyone have a magic trick or do I need to go on the tracker and wait for a couple of releases to have it fixed? :(

Would you mind attaching the test app so we can play around with it? Looks like QMdiArea does some nasty activation tricks upon QEvent::WindowActivate. Perhaps you could try filtering it (and possibly QEvent::WindowDeactivate too) out from the inner QMdiArea...

hi,
does it happens also when mdiArea in child window have no children? i would suspect that activation of child window may bring mdiArea to front, but it's only a speculation...

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Originally Posted by jpn

Would you mind attaching the test app so we can play around with it? Looks like QMdiArea does some nasty activation tricks upon QEvent::WindowActivate. Perhaps you could try filtering it (and possibly QEvent::WindowDeactivate too) out from the inner QMdiArea...

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Thanks for the hint I'll try that. FYI the test apps are Edyuk 1.0.0 (SVN HEAD) and Monkey Studio 2 (still in private beta test so I can't redistribute it) but I'm willing to bet that the simplest subset of nested QMdiArea will yeld the same activation behavior...

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does it happens also when mdiArea in child window have no children? i would suspect that activation of child window may bring mdiArea to front, but it's only a speculation...

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I have no idea... The child mdi area always have at least a child (always a single one in Edyuk and one or more in Monkey Studio...)

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Originally Posted by fullmetalcoder

Just to make sure the problem does not come from my code I checked another app using the same QMdiArea nesting and was able to reproduce the bug...

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I somehow expected this to be a minimal compilable example or something like that. :)

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Does anyone have a magic trick or do I need to go on the tracker and wait for a couple of releases to have it fixed? :(

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The "magic trick" goes here:

Code:

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class InnerMdiArea : public QMdiArea
{
public:
    InnerMdiArea(QWidget* parent = 0)
        : QMdiArea(parent) { }
 
    bool eventFilter(QObject* object, QEvent* event)
    {
        return event->type() == QEvent::ApplicationActivate
            || event->type() == QEvent::ApplicationDeactivate;
    }
};

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As the class name suggests, use this as the inner MDI area and everything should be fine. ;)

PS. The reason this works is that QMdiArea installs an event filter on QApplication and QObject::eventFilter() is virtual..

Neat! :) It works just fine but the only limitation is that it take place in the inner area which is loaded from a plugin so it will put some restrictions on plugins development. Better than nothing anyway...

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Originally Posted by fullmetalcoder

It works just fine but the only limitation is that it take place in the inner area which is loaded from a plugin so it will put some restrictions on plugins development.

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Well, in that case you could do it differently. Just detect such nested mdi area in a way or another and do:

Code:

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qApp->removeEventFilter(innerMdiArea);

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You may also implement eventFilter in some external QObject and install it after QMdiArea creation from plugin.