Emoji shortcodes wait for the colon to land
Half-typed shortcodes now stay put as letters while the menu offers the emoji you meant. The menu also ranks matches at the start of a word above the ones buried mid-name.
Type a colon and the start of a shortcode in the compose box, and the letters stay right where you put them while the menu under the caret offers the apple emoji. Press Enter or Tab, or click, to drop the emoji in. Close the colon yourself, and the matching emoji appears the moment the colon lands, with no leftover colon behind it. Even a colon and a single letter sit still now instead of turning into a lettered emoji before you reach the fruit.
Credit goes to xHeaven, who taught the box to wait for the closing colon. The rule is the same in the box you type in, in the preview, and in what the server saves. A shortcode becomes an emoji only between two colons or when you pick it from the menu. Typing one colon and nothing else leaves plain text, including after you post. Picking still takes Enter or Tab, or a click, and adjacent shortcode pairs combine into one emoji.
The menu now sorts its eight suggestions into three tiers. Names starting with what you typed come first, then names with a later word starting with it, then names containing it anywhere. Each tier goes shortest first, and the highlight marks the matching word, so a start-of-word match later in a compound name is highlighted rather than an earlier substring.
One catch. Eight is all you get. Fill the slots with word-start matches and a common inner match falls off the list.