[Feature Request] Add styling support and/or property to identify a shape that is currently being drawn

[neodescis]

Is your feature request related to a problem? Please describe.
I would like to style a shape that is currently being drawn differently from the other shapes. Currently there is not a very good way to identify a shape in this state. Right now I am using change and finish events to track it and alter the styling accordingly, but that is less than ideal.

Describe your proposed idea for the solution to this problem
I'd like to see support for this more like how I can identify and/or style selected shapes via the selected property.

Describe alternatives you've considered
As stated above, watching for change and finish events on a shape can help determine a shape actively being drawn.