MDI sub-window invalidates set main window title

For the QMdiSubWindow - the variable d->originalTitle stores original title.
When the title is changed right after the QMdiSubWindow is called to be shown (before any events are processed by event loop), the QMdiSubWindow::eventFilter() doesn't update the title when the sub-window has min/max/close buttons disabled.

In the QEvent::WindowTitleChange case in QMdiSubWindow::eventFilter() following condition is false:

d->controlContainer->menuBar()->cornerWidget(Qt::TopRightCorner) == maximizedButtonsWidget()

(Which is apparent as there are no min/max buttons). And therefore d->originalTitle is not updated. Resulting in faulty behaviour of showing the previous title instead.

QMdiSubWindow is ofc maximized programatically before calling show.