bug 332596 Deleting a qstyled KLineEdit causes crash

The bug was as follows. When a WrittenPracticeWidget using a KLineEdit styled with a qStyleSheet that has focus is deleted this triggers a focus changing event, but the QStyleSheet returns a style that has already been deleted and causes a crash when the invalid style is applied.

The obvious solution of responding to the destroyed() event doesn't work , because the destroyed() event happens after the crash.

In order to fix this bug, I transistion focus away from the KLineEdit before the focus change preceding deletion. The virtual function, WrittenPracticeWidget::objectDestroyed, avoids having a practice mode switch statement as large as this comment at each delete event.

Transitioning to helpLabel was chosen arbitrarily.

Todo:

When frameworks/kde5 is implemented remove this code , if the bug in Qt (returning a pointer to a deleted stylesheet) is fixed. If this function is removed then the entire inheritance path can be removed.