I usually play on a mac. One time when I was playing I noticed that I couldn't pick up items from my survival and creative inventory on single-player and multi-player and I had to drag the item. This made it nearly impossible to craft. So, what I did was I made separate accounts on my mac and I played just Minecraft there. But, that ended up happening after a little bit, so I made a new account. Eventually, I went down and tried to use my Windows 7 computer, that after a couple minutes, the same thing happened. I looked this issue up and no one had had it. It might be just my account. My account is creepergmkg. This happens to all versions-- pre and post 1.8, and with and without mods (I stopped using mods though-and those separate accounts on my mac didn't have mods on them)

Thanks!
creepergmkg