Right-clicking to split stacks works only sporadically. Roughly every 4th or 5th right click will register.

Note: to get Minecraft to even work in fedora 18, I needed to download a newer version of Leightweight Game Engine and install the precompiled binaries of a few .so and .jar files just to get past the black screen on initial loading.

See this helpful post for exactly what I did. I hope this is not part of the bug.

I've attached a video showing you the problem I have. In the video, once you see me pick up all 8 apples, I try to right-click to split them into individual item spots in my inventory. You can't hear it, but I right click about 50 times during this video, only maybe 5 of which actually register.