Add QMdiArea::AlwaysShowSubwindowNameInTitleBar
This option makes Qt always put the active window name into the title bar of the main window, even in tabbar or floating window mode.
This patch is extremely hackish, because the original design of the title update in Qt in weird. There is are model/view and all the children of QMdiArea manage the parent's title in a "distributed" (read, random) way.
See this bug: https://bugs.kde.org/show_bug.cgi?id=475172