Using GMS light functions draw_light_define_point and so on once the light got turned on with draw_light_enable it stays on even after you comment out all lights and reload. 

Is that expected behaviour? I didn't find anything on a quick search here in the forums or in the documentation.

Greetings and thanks for this amazing tool!

Using GMS light functions draw_light_define_point and so on once the light got turned on with draw_light_enable it stays on even after you comment out all lights and reload. 

That's how GameMaker works in general - nothing to do with GMLive. You can also see this behaviour with draw_set_color, draw_set_alpha, draw_set_font, draw_set_halign, draw_set_valign [...] - all draw state functions change the state and it stays that way until you change it again.