Dynamically changing QLabel background colour

[T4ng10r]

In GroupBox I've placed few QLabels. Now - depending on which of this labels I click - I want to change background colour of one of those QLabel.
I've tried

QPalette	palette = label->palette();
if (somethink)
 palette.setColor(label->backgroundRole(),QColor(Qt::blue));
else
 palette.setColor(label->backgroundRole(),QPalette::Window);
label->setText(someText);
label->setPalette(palette);
label->setAutoFillBackground(true);
label->update();

QPalette	palette = label->palette();
if (somethink)
 palette.setColor(label->backgroundRole(),QColor(Qt::blue));
else
 palette.setColor(label->backgroundRole(),QPalette::Window);
label->setText(someText);
label->setPalette(palette);
label->setAutoFillBackground(true);
label->update();

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In the result - if i click on QLabel which should change background of others - no effect. When label->setAutoFillBackground(true); is set - widget turns him self into black block. When i click on widgets which should change background - then they are changing it to a proper one.

Then I've tried Style sheets. In places where I was changing palette - now I've placed

label->setStyleSheet("QLabel { background-color: blue }");

label->setStyleSheet("QLabel { background-color: blue }");

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and where I reset

label->setStyleSheet("");

label->setStyleSheet("");

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No difference.
PS. I'm coding under Windows XP. My application is using different styles like QPlastique, QWindows, QMotif - under each of them I see no effect from above code.