QmlDesigner: unregister the qml designer widget from the design mode

Change-Id: I43bd032272e2e472a9a1a3e35993caf8c0ccfeda
Reviewed-by: Thomas Hartmann <Thomas.Hartmann@digia.com>
QmlDesigner: Fix aligment of text

We are now have three different bounding rectangles,
for selection, the painted content and a combination of the two.

Task-number: QTCREATORBUG-11054
Change-Id: I4e40056f2811eb8e738e571f4a7fded16fa73a68
Reviewed-by: Thomas Hartmann <Thomas.Hartmann@digia.com>
QmlDesigner: Fix clipping

Change-Id: Iad309614756c5d57830382a4548b3faa9ed6b658
Reviewed-by: Thomas Hartmann <Thomas.Hartmann@digia.com>