qsystemtrayicon opens many windows , need one

When clicked multiple times, a qsyste开发者_StackOverflow中文版mtrayicon should open only once. How is it possible?

That's up to you handle how many instances of a Window are fired up. QSystemTrayIcon has nothing to do with it. You most probably are creating a widget each time the system tray icon is clicked, instead of using just one and calling QWidget::show() and QWidget::hide() respectively. That's the best shot i can take at your issue, given the thin description.