Re-enable "component tree" in Android Studio

If you are looking for the component tree, go on the bottom left of Android Studio then click on the square (the one who show/hide the tool on the left, bottom and right) then on Designer. A new tab should be on the right part of android studio, with gradle and maver project.

I lost mine too, and then realized that they just moved it to the left side of the screen in the latest Android Studio 2.2 Beta 2. It took me a good 10 mins to find it.

A simple way of doing this --> just press shift+F12. If this does not work then, go to windows menu --> Restore Default Layout.