How to highlight a polygon or a vertex under the pointer in Python? I am trying to figure out how to highlight a polygon or a vertex that could be under the mouse pointer in Python for 2.80. The highlighting is just a visual indication. I realize that I will be needing to scan for components and draw the shape, but just do not know how. 

thanks
Look at these templates:
1) Operator Modal View3d Raycast: With this you will find the polygon of a mesh under the mouse cursor.
2) Operator Modal Draw: This contains an example of using BGL for drawing in 3d view. With this you will be able to draw the edges of the polygon you find from raycast.