how to change the color of a top widget ?

[fanat9]

Thru palette for your widget.

In sources it may look like this:

QPalette palette = this->palette();
palette.setColor(QPalette::Window, QColor::fromRgb(255, 0, 0, 255));
this->setPalette(palette);

QPalette palette = this->palette();
palette.setColor(QPalette::Window, QColor::fromRgb(255, 0, 0, 255));
this->setPalette(palette);

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take a look on http://doc.qt.nokia.com/4.6/qpalette.html