If you open a dialog (for example a UML Class properties window), then alt-tab
to another application (for example a document with details of the class), then
alt-tab back to the dialog, the dia document window is shown. However, when you
now Ok, or close the dialog, the document window is minimized and focus returned
to the other application. Surely as a child of the DIA window, control and focus
should return to the parent document window.