Usual workflow on the admin/build/simpletest page is :
1 - Run tests : Hit 'Begin' again
2 - Look at the results at the top of the page
3 - If errors, fix the code in the module (or in the test...)
4 - Goto 1 : Scroll down to the bottom of the page and hit 'Begin' again.
Having the 'Run tests' fieldest replicated at the top of the page would avoid repetitive 'scroll to bottom'.