Add option to make layer referenceable

Hey, longtime user of Flipaclip here. I really like what you guys are doing with the beta and all the new ideas you’re planning to implement. One thing I think would be a great addition is making a layer “reference-able”, like procreate’s feature. To explain more, if you make a layer have the  ‘reference’ option, like line-art for example, people can then make a color layer below it and are still able to use the bucket tool without disrupting the lineart. 

Thanks for listening!