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Thread: BUG: adding 5 child-widgets to a widgets layout makes widget invisible

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    Exclamation BUG: adding 5 child-widgets to a widgets layout makes widget invisible

    See http://www.qtcentre.org/threads/2995...-how-its-added.

    This has nothing to do with the particular child-widget used.

    In any order 4 is the maximum number of child widgets a layout can handle (even via sub-layouts or addRow where one row equals one child-widget) before the widget becomes invisible.

    So confirmed with Qt 4.6.2 under Windows 7.


    See submission at http://bugreports.qt.nokia.com/browse/QTBUG-10008
    Last edited by planetLars; 18th April 2010 at 12:27.

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    Default Re: BUG: adding 5 child-widgets to a widgets layout makes widget invisible

    You mean this doesn't work?

    Qt Code:
    1. #include <QtGui>
    2.  
    3. int main(int argc, char **argv){
    4. QApplication app(argc, argv);
    5. QVBoxLayout *l = new QVBoxLayout(&w);
    6. for(int i=0;i<10;i++) {
    7. QPushButton *b = new QPushButton(QString::number(i+1));
    8. l->addWidget(b);
    9. }
    10. w.showMaximized();
    11. return app.exec();
    12. }
    To copy to clipboard, switch view to plain text mode 

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    Default Re: BUG: adding 5 child-widgets to a widgets layout makes widget invisible

    Hi,

    this does work. I phrased too general obviously.

    I checked other parts of my code. I have 2 QWidget windows. The first accesses the seconds position when the first gets moved. This appears to work as long as there are 4 child-widgets inside. Having 5 leads to the second window being invisible. So it may even be a bug in my code or something I can work around now. I am going to check further with the first window (I stripped the code related to the second window and that "BUG" occurs) and report back.

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    Default Re: BUG: adding 5 child-widgets to a widgets layout makes widget invisible

    Please ask your invisible widget for its geometry. It is possible you just moved it out of the screen boundaries.

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    Default Re: BUG: adding 5 child-widgets to a widgets layout makes widget invisible

    Hello,

    it appears that a void moveEvent(QMoveEvent*) gets fired on void show() and the moveEvent code gets executed before the show code which is where I initialize variables for the second windows position. As the moveEvent uses these variables the second window gets put to some outside random location thus being invisible.

    Not a bug after all (except if that event mechansim is unintentional or not wanted). Apparently the randomness of the uninitialized variables is "outside screen" for 5 child-widgets and "inside screen" for 4 child-widgets.

    Thank you.

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    Default Re: BUG: adding 5 child-widgets to a widgets layout makes widget invisible

    Quote Originally Posted by planetLars View Post
    Not a bug after all
    Yeeeay... another one bites the star dust
    (except if that event mechansim is unintentional or not wanted).
    Of course it is intentional.

    Apparently the randomness of the uninitialized variables is "outside screen" for 5 child-widgets and "inside screen" for 4 child-widgets.
    Not really

  7. The following user says thank you to wysota for this useful post:

    planetLars (25th April 2010)

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