Change cursor to hourglass/wait/busy cursor and back in Qt

Qsiris solution is “widget wide”. If you want to change cursor for your whole application then use

QApplication::setOverrideCursor(Qt::WaitCursor);

and

QApplication::restoreOverrideCursor();

Note: As @Ehsan Khodarahmi pointed out, the cursor will NOT change until triggering next QT event or calling QApplication::processEvents() manually.