Zoom rectangle

[Manjiri Andhare]

Hello All!
 I'm working on Windows 2000 nad IIS. With mapserver, I have created a
basic web application for displaying maps with layer turn on/off and zoom
in zoom out functionality.
For zoom in/out i have used zoomdir but i'm not sure about the basic
difference between using zoomdir and using zoom.
In Template reference it is mentioned that zoom dir is used to make the
zoom direction persistent. And for me zoomdir is working fine with the only
exception is ..if i click on the map, it zoom to that point as a center,
but if i select the radio button for zoom in and click refresh button(a
asubmit button), then the map starts shifting on the right bottom corner
instead of of zooming in into the center of the map. Obviously, I haven't
wrote any code to do that and I think thats the reasont that its behaving
like that. I didn't write any java script code to handle the click event of
the submit button.
If anybody knows the reason behind it and what code should i write so that
when i click on the refresh button, the map should zoom to the center
instead of moving to the right bottom.
Another question that i wanted to ask is, how to draw a rectangle to let
the user select the area to which he/she wants to zoom. If anyone has
already done this, please tell me how to do that.
Thank you all in advance,
Manjiri Andhare
GIS coordinator
PA Fish & Boat Commission
U.S.A.