US Patent 9471192 Region dynamics for digital whiteboard

Roughly described, different drawing regions are opened for different users on the same whiteboard. Each drawing region has its own set of line appearance properties, which the user can set with a toolbar. Lines drawn in a drawing region adopt the line appearance properties then in effect for that drawing region, which also apply to replications of the line on other devices in the collaboration session. As the user draws toward a boundary of the user's drawing region, the boundary automatically moves so that the drawing continues to contain the user's drawing activity.