Hot bar Repeated Switching

Everytime i play minecraft my hot bar repeatedly changes which slot it is. An example would be i am chopping down a tree and with an axe then the slot changes to a pickaxe.

What I expected to happen was...:
My hot bar not to change unexpectedly

What actually happened was...:
My Hot bar changed unexpectedly

Steps to Reproduce:
1. Download the Minecraft adventure map Diversity
2. Play the adventure map
3. Your Hot bar will then change with out you doing anything