Hi friends!
Some folks pointed out that last will glitches (skipping to the end, deleting the last letter you wrote, etc) are caused by hotkey issues. So I created a hotkey profile in which literally every single command is disabled except for the ones used in chat and replay viewing. The last will box still glitches sometimes, but it's a lot better than it was before I changed my hotkeys.
I think you can take my hotkey file and drop it straight into your "Hotkeys" folder in your SC2 program files. The "Hotkeys" folder is near your "Banks" folder. Here's the file chain on my computer, so that you can see where to look: Documents\StarCraft II\Accounts\71578097\Hotkeys
The forum didn't let me directly upload a .sc2hotkeys file, so I put it into a zip folder.
I hope that this helps!