Restore the possibility to open separated editor windows with a double click.
There should be a choice in the preferences to choose between:
1/ (the actual behaviour):
Double click open editor spliting the arrange window
(and holding ALT key + double click to open the editor in a separated window)
and
2 / (a "new" behaviour):
Double click open directly a separed window.
(this time: Holding ALT+ double click to open "inside" the splited arrange page)
