The emoji picker shouldn't automatically disappear after an emoji is picked. This should either be an option in the settings, or just not a thing in the first place. It's annoying to type in multiple emojis from the picker (that you don't know the name of) and have to open it up multiple times, wait for the emoji you want to see to load, then pick it. This is the benefit to the emojis being in a pop-out window.

You can hold shift when clicking an emoji, and the picker will stay open. Can you try that?

Fixed