Unsolved QToolTip in SubDialogs does not hide properly

[WWebber]

I have a main window and a QDialog child window. In the main window the tooltip disappears when I move with the mouse, but in the child window the tooltip behaves different and disappars after the timeout.
I already tried to hide the text with QToolTip::hideText() in the child window, but the tooltip stays active. When I move the mouse on another control with a tooltip, the new tooltip will be displayed immediately, but moving in an empty area of the dialog does not hide the text.
Is there anything I have to reset to make tooltips working also in the child dialog, before I open a child window?

[Christian Ehrlicher]

Please show a minimal, compilable example to reproduce your problem. I'm not aware of such a behavior.

[WWebber]

Not so simple, as the dialogs are part of a main application. My main dialog is a non-modal and the child windows of it are modal. Maybe it is related to this..