how to detect insertion point

[larry at significantplanet.org]

Hello,

I have several fields... myField1, myField2, etc.

When the user clicks within a field, I want to detect the (?? selection, insertion ??) and run a script.

I've experimented for over an hour with no luck.

The only thing I found that sort of works is:
on mouseEnter
  do stuff
end mouseEnter

The problem with that is that one of the things I want to do is change the color of the field while the script is doing stuff and only change back to the original color when the stuff is finished, and not when the mouse leaves.  It is too clunky to require the user to leave the mouse in the field while the stuff is being done.

I hope that makes sense.
Thanks for any help.
Larry