Help/WidgetDesigner: Fix wrong connection

Broke with 8fc7035b18e265910795b27cf1be346dd900b942

Change-Id: Id34e942cc521344b4b2ebf81c479451cfc5f222c
Reviewed-by: Nikita Baryshnikov <nib952051@gmail.com>
Reviewed-by: Karsten Heimrich <karsten.heimrich@digia.com>