Transparent Widgets and alpha blending

[john_god]

You have to set attributes in the constructor of your widget

setAttribute(Qt::WA_TranslucentBackground,true);
    setWindowFlags(Qt::FramelessWindowHint | Qt::WindowStaysOnTopHint );
    setWindowOpacity(0.5);
 
    bool t=testAttribute ( Qt::WA_TranslucentBackground);
    qDebug()<<t;

setAttribute(Qt::WA_TranslucentBackground,true);
    setWindowFlags(Qt::FramelessWindowHint | Qt::WindowStaysOnTopHint );
    setWindowOpacity(0.5);
   
    bool t=testAttribute ( Qt::WA_TranslucentBackground);
    qDebug()<<t;

To copy to clipboard, switch view to plain text mode 

The Qt::WA_TranslucentBackground is mandatory, the other flags I dont remember if they are, check the Qt documentation. Also, in linux, you have to enable transparency in your X-window system. In my machine, without compiz enabled, it doenst work, but with compiz works fine.