Transparent background on QLabel on transparent QWidget

[codeslicer]

Yes, I know. I read all of the threads which had to do with this, but I couldn't extract any information which could have been helpful to me.

Here's what I need:
I am trying to create a custom QWidget which doesn't use the default system frame, but instead its own. The frame is irregularly shaped, and I want to use setMask() to show only the opaque parts of the QWidget "Dialog". Now, everything is fine, the dialog is transparent as it should, but the images aren't. I have png images which use transparency and on the dialog, the system background shows up, which makes it not so transparent after all. I tried using:

labelWithImage->setMask(QPixmap("/app/labelImage.png").mask());

labelWithImage->setMask(QPixmap("/app/labelImage.png").mask());

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but nothing happened. Then I tried setting the Qt::WA_NoSystemBackground, or Qt::WA_ContentsPropagated, but that resulted in weird results. I know this is possible because I saw some people do it in this thread. Look at the apple image on the first post. Yes it's ugly but how did they implement it? They just didn't include how to do it

An example:
As you can see, the background of the label isn't transparent. Now I have an image where the transparent pixels show up as that color. How would I solve this?

[codeslicer]

... No one even replied here. But I finally solved it using:

void resizeEvent(QResizeEvent *e){
    QDialog::resizeEvent(e);
    //label_2->setAttribute(Qt::WA_ContentsPropagated );
    QPixmap pixmap(":/new/prefix1/stand.png");
    label_2->setPixmap(pixmap);
    label_2->setMask(pixmap.mask());
    QRegion reg(frameGeometry());
    reg-=QRegion(geometry());
    reg+=childrenRegion();
    setMask(reg);
}

void resizeEvent(QResizeEvent *e){
    QDialog::resizeEvent(e);
    //label_2->setAttribute(Qt::WA_ContentsPropagated );
    QPixmap pixmap(":/new/prefix1/stand.png");
    label_2->setPixmap(pixmap);
    label_2->setMask(pixmap.mask());
    QRegion reg(frameGeometry());
    reg-=QRegion(geometry());
    reg+=childrenRegion();
    setMask(reg);
}

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Also, I used 2 horizontal spacers to center my object in the widget. Otherwise the Mask would cover the wrong part of the widget. But I have a question. My widget is a rectangle with 4 "fixed" size corners and then "expanding" size spacers, which resize depending on the window. When I resize it it seems to flicker a lot, maybe because it's an irregular shape. (There is this "stand" on the bottom which makes it look like commonly used electronic gadget) So basically it's not exactly a rectangle. And how do I make a size grip on the irregular object? Thanks for all the helpful people like wysota and marcel who helped me with my previous problems.