you may want to get the asp.net control's or html element's
id when clicked or other events fired for that element.
It can be done in many ways using jquery or simple javascript.

It's a very common requirement to show hint in textbox when empty
and when textbox gets focus hint goes away.now a days many websites
implemented showing hint.there are many ways to do that by jquery.

If you want to run your software with same width and
height as your monitor's width and height then
implement the following technique in your application-

It's a very logical requirement to validate user entered email
address before processing anything.in this way you will
never get a invalid email address when you do something
with email address like send email,etc.

the following javascript codes will help you find
out the browser details by some javascript functions