When i place shadow_stencil=4; in my function main. I see blue artifacts.

There can be many reasons for shadow artifacts. Do they only happen with 4, but not with 1, 2, or 3?

They happens with 1,2,3 too.

It looks indeed strange - not like a normal stencil shadow mistake, such as an open mesh. Possibly it's a side effect of screen entity drawing bug, but that one should only happen when no level is loaded.

If the project is not too big, you can send it to the support - we'll then look into it.

My project is too big to send it by e-mail(about 90Mb). This bug appear only in new version 773.

Stencil shadows in 7.73 are no different than in the versions before. I think your problem is caused by something else. If you can't strip it down from 90 MB, you could also upload it to our server: ftp.opserver.de, user: anonymous, pass: anonymous.

I upload my project on ftp.