Does anyone remember the control panel Respond? I found a download for it, http://download.cnet.com/Respond/3000-2094_4-3836.html

Its supposed to provide limited pre emptive multitasking to System 7 on up. Its also known as red shed threads and I belvieve I found the source code to it here,

http://rentzsch.com/trac/browser/trunk/Carbon?rev=88