To make the tabs "switch" I basically hid and showed the IE windows, by their window handle. I think Win32 allowed you to do that to windows of other applications, back then.
Create a tray-icon, and iterate over all the windows. Any window that was on "this" desktop would be shown, all others would be hidden.
When the user hit the key to go up/down through the virtual desktop list (I think there were four), we'd update the hidden/visible state of all appropriate windows.
Written in C using the Win32 API and only a thousand lines of code or so. It was a pretty reliable and useful hack at the time.
https://web.archive.org/web/20040428022140/http://www.steve....
I guess that brings us back on topic!
There's been some amusing ones even not so long ago, like this one:
http://kylehalladay.com/blog/2020/05/20/Rendering-With-Notep...
edit: Bad example, they are using WriteProcessMemory. Still a lot of fun, but not the same. I was thinking of this:
For better or worse this sort of thing still works just fine for apps which still use Win32 controls. All that's really changed with regards to UAC is non-privileged apps can't mess with privileged ones.
(I had a version that added itself to the registry to auto run at startup, but even my teenage self thought that was a bit too far).
I taught a coworker (who had never touched any code before) some of it. After a few months he moved on to do data entry for another company. When I saw his title on LinkedIn change to "automation engineer" after a while I was curious and had to ask what happened. He had automated most of his data entry job. The bosses got curious and asked to share his secret which he did, got a fat raise and a nice title. Sadly, most of his team was let go, but I'm happy I helped him become a programmer.