Qt :: Type of popup closes automatically on X11 / i3 .. is this behavior guaranteed?

Question

Is it guaranteed that when the user clicks outside the popup in the parent window, the popup closes and / or can somehow change this behavior or influence? I see this behavior in X11 using the i3 window manager.

I would like to have functionality that apparently provides a popup: Modal relative to the parent (i.e. if the user clicks somewhere in the parent window .. the popup will not let him pass, but instead will trigger an event that I I can handle it myself .. for example, by closing the popup explicitly).

Edit

I found that the usual "closeEvent" can be used to reject the closing of the popup. However, it is still mysterious to me whether the "modal" behavior is guaranteed and automatic closing is guaranteed.