[REGEDIT] crashes under Windows

use our regedit from 0.4.15-dev-5943-g93dface executed under Windows.

Select the root in the treeview "My computer".
Then select "Export" from the Menubar.
And choose a filename and press "save".

It will immediately crash.
The same crash happens if we select that option from the context-menu of the root-entry.

As far as I tested it will not crash when doing that same procedure, if the selected treeview-element is not the root-element.