Hi soma115, I had the same problem and I can asure you that there's no software or cheap solutions for this headache... Apple hasn't take the responsibility for this manufacturing fault till now and I don't think they will. The option that the genius gave me was to replace the display, but that wasn't my intentions taking into account the price... After almost 2 years working with the half of my display and daily internet searching, I decide to talk with a friend who is an expert in cold welding and showed him a youtube video with a alternative solutions that implies to re welding the left display cables. So I left him my iMac 27" mid 2011 Core i7 3.4Ghz with the same hope that a father has when left his son in the hands of a doctor for a crucial medical surgery, and thank God everything went good! now I have my display working in it's whole extension and pixels. Here's the link with the video I've mentioned. https://www.youtube.com/watch?v=gSzmyqQFZ2M
Cheers,
Carlos