When the signal aboutToShow of a menu associated to a QToolButton has registered receivers, the popup menu is not placed at the same place than when there is no receivers.

With receivers, the menu popups just bellow the mouse, which selects the action at cursor position. The menu then disappears when the mouse button is released. The menu is then very difficult to use.

Without receivers, the menu does not appear under the mouse cursor and is not closed when the mouse button is released.

The code in QToolButtonPrivate::popupTimerDone() uses a different size hint if signal aboutToShow has receivers or not.