Detecting change in a textbox

Up to now I've been detecting when a textbox value changes by subroutines like this

Please Login or Register  to view this content.

But now I've learnt to restrict users to entering integers only, using

Please Login or Register  to view this content.

Now, if I just use the second of these, it detects when user enters numbers, but not when user deletes something. If I use both the routines, then pressing alphabetic keys makes the system think that tbox.value has changed, when it hasn't. What I want is to detect when the text changes, or to detect keypresses for delete and backspace as well as numbers, but to ignore keypresses for the characters that don't do anything because of the second subroutine above.

Basically, I don't really understand how to use these keyup and keypress subroutines. Any help would be appreciated.

Originally Posted by shg

The simple approach would be to just validate the content on exit.

Yes, I suppose I could use IsNumeric(tbox.text) after the event. Not quite as elegant as preventing the user from inserting alphabetic characters in the first place, but perhaps more transparent to the user. Thanks.