floating window closely aligned with another element?

Hi All,
I have a simple html table with the first row containing column names.
I would like to be able to click on a littlel icon in the column
header, and 'pop up' a little window that lets me set options related
to that column. I haven't found any examples of how to bring up this
pop up window and, more importantly, how to align it to table cells so
it looks professional.

One idea I have is the JSCalc
(http://www.themaninblue.com/experiment/JSCalc/). Imagine the 'JSCalc'
tab is the column name and the calculator window appears below it. If
the column is right next to an edge, then the 'pop up' window has to
adjust its location.

Any way, I hope you get the idea. Can anyone recommend any references?
Thanks.