Chrome 6 introduces a new Wrench menu that unifies it with the old Page menu. To save space and eliminate clutter, the UI leads decided to merge common elements into button items. Cocoa allows putting custom items in menus using -[NSMenuItem setView:], but none of the typical menu interactions that users expect are provided. Missing are hover states, menu closing on selection, and non-sticky mode. Menus on Mac OS X have two modes of interaction; the first is typical of other platforms: click to open and click to select an item. The other is non-sticky mode, where the user can click the menu open and, without releasing, drag to the desired item, and release to select it. Custom buttons were written to implement all these behaviors, as well as to change their appearance.
Another feature of the menu is to be able to use the zoom buttons and have the page update while the menu stays open. The issue in implementing this was that after the zoom button messages the renderer to zoom, the acknowledgment (containing the actual zoom level) comes back asynchronously to the I/O thread, which then forwards the Task to the UI thread's main event loop. When a menu is running, though, a nested event loop is run that blocks that UI event loop. To fix this, the callback on the IPC thread is special-cased to post the Task in a way that both the modal menu loop and, if a menu is not running, the main loop can process it.