ENH: refs #990. Add simple locking mechanism to slice/window updating
ENH: refs #990. Add simple locking mechanism to slice/window updating

This allows us to update as the user slides the sliders

jcfr/Midas,jcfr/Midas,jcfr/Midas,jcfr/Midas,jcfr/Midas,jcfr/Midas