Before 0.12.1 I was able to take items out of my inventory and throw them on the ground by holding the item in the item bar. I have not been able to do this since. Fixing this would be helpful especially when playing in multiplayer when accidentally picking up someone else's items after they die.
This has been fixed as of 0.12.1 build 10. https://docs.google.com/document/d/11tUgbssVOAwT0xD1_sB_CJV3Ugl4hZSdVDBbFwayxXA/pub