Edit mode not exiting cleanly on "Back"

I have a custom web page with lots of form fields.

I've redefined F2 to be the "back" key.

What happens is that the screen is not resetting the reverse mode.  If I 
am in an edit field and in edit mode and hit back, the reverse mode is 
carried over to the previous screen.  If I enter that screen via a link, 
it displays correctly.  If am not in edit mode when I hit "back",  it 
displays correctly.

I've posted the jpeg at http://www.seiner.com/reverse.jpeg

Can anyone shed any light on this?  Where do I look to fix this?

--Yan