Have to click and hold and drag to take block to or from creative interface

Have to click and hold and drag to take block to or from creative interface on multiplayer and singleplayer

What I expected to happen was...:
I just click with left mouse button and move my mouse where i want to put block on my toolbar then click left mouse button again and the block will go there

What actually happened was...:
I have to click and hold and drag to move block to or from interface with right or left mouse button

Steps to Reproduce:
1. I was playing on a creative server (hub.thecrafters.net http://thecrafters.net)
2. I suddenly started experiencing glitches in placing blocks
3. Server crashed and kicked everyone off, when rejoined people couldn't leave Hub
4. Before joining server you saw that it showed you could not connect (Attachment 'Image 5') but when you click join, you joined just fine
5. Next day I log on, build stuff, log off
6. I log on again an hour later and i the bug (Have to click and hold and drag to take block to or from creative interface) showed itself
7. Launcher did not crash or anything bad
8. Moderator on server tried to help me, we tried re logging, killing my character, and different areas, nothing worked
9. I reinstalled minecraft
10. Didn't fix