After my minecraft updated to 1.4.2 I couldn't split item stacks. It's really hard to play the game when I have to have 2 stacks of whatever it is to craft something else.
I am having the same issue. I know it is not a hardware or system sofware issue. The game recogizes when you change the keys (becasue that is what i tried to diagnose the issue) but that is all. I use right click normally and i can not "Pick Block". Does anyone know whats going wrong becasue i may have to go back to a previous version. Kattyia, do you have a macintosh?
Minecraft 1.4.2 bug