Btw, the JDBC driver connection (com.microsoft.sqlserver.jdbc.SQLServerDriver) looks like this now:
jdbc:sqlserver://${#Project#DBHost}:${#Project#DBPort};databaseName=${#Project#DBDatabase};user=${#Project#DBUsername};password=${#Project#DBPassword}
(the last one shows up as PASS_VALUE)
It works in the Database configuration screen.
Aaaaaah, I found it. I was editing the properties at project level. When I was checking the properties at environment level, I found that my freshly made DB connection had no parameters yet!
So I added them there, and now it works. :-)
