The Samsung Galaxy S4 has a nice Sidebar that allows you to quickly access icons from any screen including apps. I must admit that I stumbled upon this feature accidentally. The sidebar appeared while I was using the phone, and I had no idea how or why. I finally figured out how to enable the sidebar though.
From any screen, you can press and hold the Escape button, located to the lower-right side of the device, below the screen. Once this is done the sidebar is enabled and will appear.
Once you’ve selected an icon, the sidebar will collapse into small tab on the side of the screen. You can tap this tab at any time to make it appear.
If you ever decide you don’t care to use the sidebar, you can hide it by pressing and holding the Escape button again and it’s gone.