Hi Mark,
Thanks, I'll look for the new build.
I haven't gone back to the page I linked, to refresh my memory of what's been said, and it's also been a while since I was actively chasing this, so apologies if I either repeat myself or speak incorrectly. I have yet to find a solution.
If I recall correctly, the program does work correctly, even under Windows 10, if run under just the right circumstances -- "windowed, with the Debugger enabled," I think it was. This suggests to me that maybe that particular combination causes the program to run in a sort of "controlled" or "captive" environment where Blitz3D has control and provides a DirectX (7 or 9 or whatever) environment that got compiled/linked into Blitz3D itself when it was compiled, "back in the 90s" or whenever -- whereas running the program "full screen" and/or without the Debugger -- and especially as a standalone .exe! -- makes the program dependent on the environment provided by the OS and its current DirectX (11?) environment. That, then, places the blame squarely on "them" in that they seem to have broken, or at least changed in a fundamental way that breaks this program, something in DirectX itself. Considering how few lines of Blitz Basic code are actually involved in The Part That Doesn't Work Any More (tm me), it ought to be fairly straightforward for someone (such as yourself, perhaps? -- who knows DirectX well enough to have created Blitz3D in the first place) to look at exactly what's going on and what's changed. Feel like looking into it for me? Pretty please? :-)
If you or anyone else are able to investigate that and nail down the exact details, someone might be able to submit a bug report sufficiently specific to get attention. I expect that reporting "this one specific feature of program written in a language processor that was written in the 1990s, doesn't work on Windows 10," isn't going to get much traction. I'd still report, it, though, if I knew where DirectX even comes from, and to whom to report it; is DirectX a Microsoft thing? I can't believe I don't know.
Anyway, thanks again for the reply. I'll pop back in here either if I have difficulty finding/installing/using the new build, or if it doesn't fix the problem.
Chris