When i paste some command on a command block the "Done" button locks.

Put the summary of the bug you're having here

What I expected to happen was...:
"Done" button stays normal.

What actually happened was...:
"Done" button locks and i can unlock it only editing the pasted command. (This happens too when you don't select the command input and press any key except ESC.)

Steps to Reproduce:
1. Opens the command block.
2. Paste everything on command input.
3. And the "Done" button locks.

Note: My Minecraft it's in Portuguese.