This is the discussion forum for the HtmlEditor. See also the HtmlEditor home page, where you can download the control, and the Documentation Wiki, a collaborative project for documenting the control.
Painting on the MSHTML surface is useless until the paintings are related to an element. And if they are related to an element they are called binary behaviors. I've used this to draw a grid and a movable helpline in the background to position elements better. Is this the kind of painting you mean?