Setting editable should not recreate the treeview in DictionaryGrid

When you set mydictgrid.editable = True, then the widget is refreshed. This has several negative side effects:

1) if you've scrolled to a specific row, then that is forgotten, which is a bad thing. Consider an application with lots of rows that are normally not edited. You have a toggle button on the toolbar to make the treeview editable when that's necessary. So you've scrolled to a row and want to edit it. After making the table editable, you'll have to scroll back to the row in order to edit it. Then you untoggle editable, and then selection and scroll position is again forgotten.

2) If you've set column titles, then those are forgotten if you toggle editable.

I think a much better solution would be to make the editable setter loop through the columns, setting the editable property for each. That wouldn't disrupt anything. It's a little more work though.