Select items in dropdown menus by typing #3761

When you have a dropdown open that doesn't already have an input[autofocus] field, typing something should select the item. Example on macOS when pressing <kbd>g</kbd>:

Example dropdown on GitHub where this doesn't work:

<img width="241" alt="" src="https://user-images.githubusercontent.com/1402241/100030047-39176900-2db8-11eb-9857-0203fc2ec1ec.png">

When https://github.com/sindresorhus/refined-github/issues/3719#issuecomment-726901443 is coupled with this, users can navigate comments, open the dropdown, and delete/edit/report with just the keyboard.