Need some suggestions on how to deal with Mouse interaction between Client and ActiveX?

This will be ultimately be interactive drawing tools which will
draw in the client picturebox?

BACKGROUND

Created (and posted this forum) an out of process program using messaging to draw lines in the Client App. This worked, but the line always appeared underneath the Client graphics.

I believe the reason for this was that the Z-Order method comes into play in that graphic methods even though originated from another process still are graphic methods, and NO z-order exists for them.

Since ActiveX supports z-order, hopefully this will allow line placement above the client graphics.

QUESTIONS:

If I create a Mouse event in the ActiveX and raise it to the client
how do I get the currentX and currentY location to the ActiveX
without delaying the client?

Any example would be appreciated.