Switching windows with something in the chat input clears the current input

On Minecraft 1.12 and earlier versions, Using Alt+Tab to switch windows while doing typing anything in a chat window keeps whatever is in the chat (Tested with 1.12.2). On 18w01a (and possibly earlier, haven't tested this), it clears the chat window, though. This becomes annoying when, for example, referencing forums or wikis for information on how to use a command.