The desktop displays graphical programs run in the local environment at a 1280 x 720 resolution.
It works with any programming language or software, but since it's built using some high-tech web wizardry, you may notice a slight delay when using a program in the desktop display versus a program installed on your computer.
The desktop display can be expanded to full-size by clicking the [] at the top right corner of the pane.
Here's what the desktop looks like with a calculator running:
You can even run software you might have needed to install locally, for example, Octave:
If you get an error like:
Unable to init server: Could not connect: Connection refused
(gnome-calculator:2376): Gtk-WARNING **: 04:44:56.136: cannot open display: :1
make sure you have opened a Desktop first!