SB is actually open-source!

[sm4llprogrammer2008]

I found the SB dev team's official GitHub profile:
https://github.com/sb

[litdev]

Hi,
That is the online version which isn't so great (incomplete at best) and some other stuff.
The main desktop IDE version 1.2 isn't open source, but can mostly be decompiled by reflection tools like IlSpy.  I think for some internal MS reasons the SB IDE source couldn't be made open source when MS discontinued its development updates, hence the varous later versions that in my opinion were all more limited (e.g. couln't run extensions for example).
SmalBasicLibrary.dll SmallBasicCompiler.exe which have the useful language stuff (rather than the IDE) can easily be fully deompiled to see how they work or be modified like sVB.

[sm4llprogrammer2008]

There's a repo on 'sb' that has Small Basic MSIs too but they're already compiled

[litdev]

Sure, but those are just the installers.