Well i have been developing a launcher for some time and i seem to have got my Minecraft Launching working but only for vanilla, my code is closed source and launcher minecraft version 1.6.4 and onwards...
I seem to get stuck on [LaunchWrapper/]: Calling tweak class cpw.mods.fml.common.launcher.FMLDeobfTweaker when ever i try to use Forge
All Libraries are there and working and everything else works perfectly, this is a very strange bug in my opinion because when it hits this line in the log file, it shuts it self down completely with no crash or anything, just standard minecraft and forge files...
Here is the error