setAttribute(Qt::WA_OpaquePaintEvent);
setSizePolicy(QSizePolicy::MinimumExpanding, QSizePolicy::MinimumExpanding);
setAttribute(Qt::WA_NoSystemBackground);
setAttribute(Qt::WA_OpaquePaintEvent);
setSizePolicy(QSizePolicy::MinimumExpanding, QSizePolicy::MinimumExpanding);
setAttribute(Qt::WA_NoSystemBackground);