PS-SCRIPTS.COM

I have some limited experience coding and scripting in C# and Javascript, though I do a lot of copy/pasting code. So I feel somewhat comfortable attempting to code small things. But I need a high-level explanation of what methods I would need to investigate to do something like this:



Is it even possible to add an element to Photoshop's UI like this? In general terms how would this be accomplished? Thanks for any help pointing me in the right direction.