Sorry, I was a bit captured by something else for some days. Thanks for looking into it.
I'm using more or less hand-made visual studio 2017 projects, and the settings are the same for allegro and all the other libraries I'm building this way. Almost all is statically linked, and I also have zip png jpg ogg lua freetype physfs alguichan in the boat. So it won't be easy to share the exact configuration, but I think I could extract the typical parameter lines for compiler and linker, if needed.
I'll try to figure out how to check out the fix you provided, so I can test it.
For the copy&paste, most of the time I'm pasting into an empty Notepad++ tab, and sometimes into outlook mail directly, without difference in behavior - either both work fine, or they don't. For the question about how I copy the text into the clipboard, I'll have to look up the code...
Edit: checked out your change, and tested. When I finally compiled allegro, aladdons and the main program with UNICODE, the fix worked. So that's nice, but to be honest, why doesn't it also work when I don't use UNICODE? Seems that the code uses _al_win_utf8_to_ansi instead of _al_win_utf8_to_utf16 which has been replaced by your change, so maybe the MBCS-part also needs some fix?