Fixed bug in enabling editor plugin when there is no items in tree.
Fixed bug in enabling editor plugin when there is no items in tree.

caio2k/RIDE,robotframework/RIDE,fingeronthebutton/RIDE,fingeronthebutton/RIDE,HelioGuilherme66/RIDE,HelioGuilherme66/RIDE,HelioGuilherme66/RIDE,HelioGuilherme66/RIDE,robotframework/RIDE,caio2k/RIDE,robotframework/RIDE,robotframework/RIDE,caio2k/RIDE,fingeronthebutton/RIDE