If a child dialog which is iconified is closed/hide programmatically, up on activation still shows and clicking on close button has no effect.
Attached example reproduces it:
Run the example
Click on button to minimize all widget
wait for 5 second (when timer fires and dialog is set to close/hide)
click on iconified window in task bar
Child dialog still visible and closing it with mouse has no effect.
This works good with Qt4