In adventure mode, some blocks and entities can be interacted with. With paintings, you are able to break them, but not place them. With flower pots, you can take flowers out, and put them in the pot. With armor stands, you can also take things from them and give them things. This is very annoying for map making.

How do reproduce:

• place a painting. Then, go into adventure, and break it.
• place an armor stand, and put armor on it. then take it off in adventure.
• place a flower pot, and then put a flower in it. take it out of the pot in adventure.

I don't know if some of these are not bugs, but I did this anyway.