There's two ways to solve this problem. If you can use DesktopX objects as pseudo Desktop Icons then the answer is straight forward and can be learned by studying how popup buttons work and how grouped objects can be made visible(pop-up all together) from a single button. Minimalism by gef has such a button that works in that fashion. If you want the real Desktop Icons to do this in DesktopX the answer is not directly. This is because Desktop Icons being visible is a configured property from the Configure DesktopX dialogue. After this property is changed DesktopX has to reload. Not nice to do in a theme. SO... make the real Desktop Icons always visible by being configured properly. Then create a mask object that is "always on top" and covers the real icons. The activation button could then toggle your mask causing the appearance that your real Desktop Icons are appearing and disappearing. No scripting should be required to implement either of these solutions.

I would really like to make a dock of some sort that is activated from a small button on side of the screen and slides out to reveal thumbnail like view several shortcuts.

Search the WC DX libraries for sidebars and see how they were built. There's some good ones out there.