The quick outline allows you to quickly see the outline of your current file without having to change focus to another view, and allows you to quickly filter the name you want (and when the dialog is done, you will be brought to the selection you did).

KEYBINDING: Ctrl+O

Doing Ctrl+O a 2nd time will show the methods/attributes from parents in the hierarchy (as shown in the image below).

The black background is a result of using it inside Aptana Studio 3 with 'invasive themes' turned on in the Aptana theming options.