Remove TreeViewControl
When MultiSelection was added by #3634 (closed), it implemented TreeViewControl to work as if the user was always pressing <Ctrl>
key.
There are two problems:
- It does not work with
<Shift>
key to select a range - It behaves at the opposite of the
<select multiple="1">
of the web client
I think we should stick with the default behavior of Gtk and HTML.