Hi WP8Expert,
I want to enable 3 column for my ATIV S I8750. Here is what I have done:
1. Change my CSC to ATO so that I can upgrade to GDR3.
2. Installed "Interop_Unlock_Helper_Debug_ARM.xap", then "BootstrapSamsung_Release_ARM.xap" and finally "EnableAllSideloading_Release_ARM.xap".
3. Also installed "SamWP8_Tools_Debug_ARM.xap" and "wphTweaksWP8.xap".
4. Ran all above apps as per guidelines
[XAP][GUIDE] Interop Unlock for WP8 + all Capabilities - xda-developers.
5. Tried to update registry key "software\microsoft\oem\startscreen" => screensize to 1.
6. It did not work and it says no registry key.
7. So I upgraded to GDR3.
Now none of above application is working and I am not able to get 3 tile start screen. Please suggest what to do in this case.