I have complex custom entities and I'd like to implement advanced manipulation like grip points of Polyline. I'm looking for how to draw a custom glyph neer the AutoCAD crosshair cursor, like AutoCAD does when you convert a polyline segment to an arc or you add a vertex (look at the image below).
I was able to implement that I wanted by combining an AcEdInputPointMonitor and a Transient Entity. Have a look to sample AsdkTransientGraphicsSampFolder of OARX 2009. In method monitorInputPoint you have to update the position of the transient entity and that's it.
Note: If you use kAcGiDirectTopmost as drawing mode (when adding transient), entity will be drawn over grips.