For the child windows we have to use showNormal() explicitly,
as the default window state logic of platforms like iOS does
not have access to the QWindow, only to its flags, and we
can not use Qt::SubWindow as a proxy for being a child window,
as that's a window flag meant to be used for MDI sub windows.
Pick-to: 6.6
Change-Id: I2b5e669f6180ffdcb75479dece38ae5e5430aef6
Reviewed-by: Timur Pocheptsov <timur.pocheptsov@qt.io>
