Add Dropdown List and Implement Mask Copying in Front-End

[KorenMary]

No description provided.

[christinab12]

Hi @KorenMary I just tested the application and found the following problems:

1. When editing an object with the paintbrush, this changes the color also in the labels layer to the instance color
2. When changing the label of an instance this will change also the label of any overlapping instance
   You can see the attached screenshots for a clearer idea of what I mean.

[christinab12]

I also tested with selecting 'Labels mask' as the active mask. If I edit an object using the paint brush on the labels mask, objects in the instance mask are changing (see attached; first image edited class mask, second image, resulting instance mask).