I've gotten bored with all random triggers that might make chatbox inactive while you are in the middle of typing. Readycheck, spar or trade request and dying to name some.
Typing in an instance, you die and keep typing for even couple keypresses and you've opened character panel, map, inventory, and maby more windows, plus opening map gives you certain lagspike. Then hit esc, and you may or may not retreat by accident as you decline the revive from cappy instead of closing the map and all the windows, and thus you are forced to sit behind instance gates rest of the fight like a noob while others do the raiding.
Other example. Typing before your group starts a heavy pull, leader does a readycheck and chatbox gets interrupted and you start firing arrows or other ranged attacks by accident (and jump, which is the fun part), starting the pull and wiping the group. No one is not happy even though they made you jump.
Related to this, removing connection between esc and retreat would be very very nice. I bet everyone has at least once in their playtime retreated by accident, when they only meant to close bags or exit chat window.