Menu lists should allow dragging from their spawner and releasing on a selection

[Keavon]

Currently, menu bar entries require clicking the menu bar button to open it, then clicking to pick a row inside. Menu bar entries should also support opening on mousedown and letting users drag down and then release on an entry. Additionally, right click and Esc should allow aborting when the left mouse is held down (either for a drag or just a click), such that the menu closes without being selected. This applies for all menu lists, such as dropdown menus as well.