Question: how to change the background color of qwidget?
Answer: m_myWidget = new QWidget(this); m_myWidget->setGeometry(0, 0, 300, 100); QPalette pal = palette(); // set black background pal. ... 
m_myWidget = new QWidget(this); m_myWidget->setGeometry(0, 0, 300, 100); m_myWidget->setStyleSheet("background-color:black;"); m_myWidget->show();