Re: QMdiArea with designer
You cannot do that. There is no logic in having the possibility to add MDI areas in Designer.
You couldn't add more than one anyway.
If you have to create a MDI interface, then do everything without designer(except maybe some components that don't depend on it).
Regards
Re: QMdiArea with designer
You can place a QFrame on the form, right click it and promote the frame to QMdiArea. Just don't insert any widgets into that frame later (it'll still be a frame in Designer, but will be compiled as QMdiArea).
Re: QMdiArea with designer