I have added the ability for people to control the option of having the header remain fixed on the top of the page, or scrolling off.
Simple go to your Profile tab in your User Control Panel
and go to the bottom of your options. There you will see three options:
Dynamic: stickiness depends on the size of your browser
Fixed: header and IM will always remain on the page
Scrolling: header and IM will scroll off the page as you scroll down
Please let me know if anyone has any technical issues with this.