Return picked points in o3d.visualization.VisualizerWithEditing() without closing the window

**Is your feature request related to a problem? Please describe.**
I'd like to immediately return the locations of the picked points in o3d.visualization.VisualizerWithEditing(), so I can do some interactions without closing the window. For example, draw lines between the picked points.

**Describe the solution you'd like**
Currently, I get the point locations after closing the window, and then I save the locations and visualize the lines in another window. But this process looks really ugly. I'd like to make it work in a single window.

Any comment is appreciated.