CVAT new UI: polygon editing

[aschernov]

My actions before raising this issue

• Read/searched the docs
• Searched past issues

Expected Behaviour

No need to choose the zone of a polygon which should be joined or clipped of a polygon. Like it was realized in the old CVAT ui:

In that case the initial polygon became white and the editing zone highlighted in red. After editing a new zone automatically joins initial polygon.

Current Behaviour

What is inconvenient?:

1. Black lines for the initial polygon and for the editing zone. Difficult to recognize.
2. After editing need to do one more action: to choose the correct zone
3. Visually old and new zones have the same colors and if we mistakenly choose a new zone we can't undo this action. Only to annotate a new zone for a polygon one more time:
   

Possible Solution

Remove the choice of zones after editing polygon's borders. Make color schemes more convenient visually. For example, it can be white for an initial polygon and red for an editing zone.