On the other hand, the CLIt is something he’ll never get to master.

You had the option. You could create a fullblown mfc application (in a couple of variants such as single document, multiple document and dialog based), but also a barebones plain winapi one. And a for a DLL too. I miss those simpler times of winapi coding, i found it fun. I moved away from windows as an OS around the time .Net 2.0 was released. Now when I look at modern windows development, I recognise absolutely NOTHING lol. Does winapi even exist still under all those layers?

It was actually quite simple from what i remember. There was a plain winapi call to control multimedia devices, the mmc api. You could send a control string to the device, such as eject, play or seek. So in maybe 4 lines of C code, this could be written.

Disclaimer: All info from the top of my head based on knowledge from 20 years ago, so take it as it is.