I am writing a very specialized app in C# that floats as a mostly transparent window over the entire desktop. I want to be able to create and pass mouse events to applicatio
Sounds like you want to do something like filtering user input.
Maybe you just need an keyboard/mouse hook.
You maybe want to take a look at the windows API call SetWindowsHookEx.
There should also be enough samples how to do that in C# available, the first thing i found was this link (maybe not the best article but should give you the idea).