My C# project references a third-party DLL for which I have the source code. Can I somehow tell Visual Studio the location of that source code, so that, for example, when I
One way you could do this would be to create another project in your solution, put the DLL source in there, and then from your main project, add the dependency as a project reference instead of an assembly reference. That should let you browse the source / step into it while debugging, etc.
There might be an easier way to do it, but I'm not aware of any at present.