views: Add support for auto-hide menubar.
views: Switching to other window should hide the menubar.
views: Hide menu bar when web view is clicked.
views: Add some asserts and comments.
win: Fix the key code of Alt.
views: Show menu when "Alt" is up.
views: Toggle the menu bar only when a single Alt is released.
views: Focus on web view when window is focused.
linux: Fix detecting Alt modifier.
menu_bar_show_ => menu_bar_visible_
Merge pull request #558 from atom/menubar-autohide

Allow window menu bar to be hidden