How to bring up the iOS multitasking bar in iOS iPad Simulator
If you're using the retina iPad simulator you will end up with the home-button-less version. Go to Hardware->Device->iPad and you'll get a simulator that has a home button you can double click.
You can also use the home button shortcut (default is cmd+shift+h) and double hit that and it will trigger the multitasking bar
The simulator hides the bezel if it thinks there's not enough room to display it. You can try rotating it, or setting it to a smaller scaling.
But you can also hit the home button via the keyboard shortcut cmd+shift+h; this also works for homebutton double-clicking.