With an open inventory the player can not throw any items out by clicking around the inventory, only by either exiting the inventory, or pressing Q
What normally happens
What would usually happen is the item hovering over nothing would be dropped on the ground
What happened
Instead of the item dropping on the ground, nothing happens
Steps to Reproduce:
1. Have something in your inventory
2. Click on the item/block
3. Move the mouse holding the item/block out of the inventory canopy, and click.
4. In previous versions the item/block would drop on the ground.
Is this Vanilla Minecraft or have you modded it?
Also check to make sure your Java is up to date.