Completion menu selections with the mouse should focus only when moused over, not on initial menu render


The completion menu that pops up when you type @ automatically selects the item the mouse is hovered over when it first renders, even if the mouse cursor isn’t moving (or, on OS X, even visible). This presents a very jarring user experience where you type “Hey @mike” then hit tab quickly and end up with “Hey ✓ Some task involving mike that you completed six months ago.” just because your mouse happened to be near the text box.

I’m guessing the only thing needed to fix this is to improve the event listeners on the menu items to trigger on mousemove (but not when the menu initializes) or mouseenter but I acknowledge there may be an edge case with those that I’m missing since I haven’t implemented something like that myself recently.