Ability to "cut off" black borders from DLP regions

[berstend]

Is your feature request related to a problem? Please describe.
When using the DLP region feature to black out certain regions (ex -DLP_Region -10,-10,-10,-10), the VNC page will show these black bars. With the black bars a lot of screen estate (in my case) is lost, that could be used to show the actual VNC content.

Describe the solution you'd like
I'd like an option to not render certain regions (like the DLP regions) in the canvas at all and have the remaining pixels take up the whole canvas (and therefore 100% of the browser viewport).

Describe alternatives you've considered
I tried using a variety of CSS trickery to achieve the same effect (cut off regions from each side of the canvas) but ran into problems where the pointer locations wouldn't match up anymore or on browser resize everything would break.

References:

• https://kasmweb.com/docs/latest/security/data_loss_prevention.html