Is it possible to customize a tree widget so that the full row will be selected and also move the items a little to the left so that there will not be that much white space?
I would like it to get it looking like this:

Instead of the default look that is this:

What you perhaps are looking for is setIndentation() which currently defaults to 20 pixels.
http://doc.trolltech.com/4.4/qtreeview.html#indentation-prop