While using chat box and get damage, the chat box will lose and the keyboard not disappear.

When I using chat box to my friend in multiplayer to test it then I was getting damage by the zombies. The chat box crash then and the keyboard not disappear. So I test in the Single Player mode, I go to the area that have a lot of zombie then I using chat box. I was getting damage by the zombies again then it same as the multiplayer.