hmm, i actually didn't think of this.
i tried to implement it now, by ran into the problem that i can set a property for any kind of widget, but then there is no unified way to initialize the actual content of the widget.
eg, for a QLineEdit i could set the data property to the old value before editing, but how do i actually set the value as text for editing? i can't do it in the c'tor, since the property won't be set yet at this time.