The PulseView NSIS installer should allow registering the .sr extension with PulseView. Ideally, this could be a checkbox (default: on), which is rather common with other installers, to give the user the choice of *not* registering the file format if so desired.
Fixed in 63ebd7fe196b3418f1a06e73642aa964cacbed93, thanks! Works fine on Windows XP, apart from the .sr files not having the sigrok logo (that seems to be not currently be supported in FileAssociation.nsh, but I guess it could be added). It's unclear whether it works on Windows 10 (maybe 7/8), needs more testing.