Why does osCommerce Admin time out?

All osCommerce sites have a session time limit.  On the site and in Admin. The one we notice the most is Admin.  There you are writing a wonderfully information and highly optimized product description.  You press save and you’re asked to log in.  A small part of you hopes it will still be there once you do, but unfortunately … not. 
So how long do you have?  About 20-25 minutes of inactivity before you will be timed out for security reasons (just like banking systems).  Unfortunately typing is not activity.  You need to invoke an action on the part of the site.  An action like saving what you entered.  But it does not have to be that and this is our trick.
If you are doing serious work then it’s a good idea to have two Admin windows/tabs open.   Work in one and leave the other open doing nothing.  If you think you have risked a time out, then go to the idle window and refresh the screen. If you are asked to log in then you passed your limit.  Log back in and that will reset your time limit and you can return to the active window and save.  Don’t forget to save.