Don't you hate it when you double-click on a .sql file and it opens a new instance of SSMS?

Open the .sql files from the "File" menu in SSMS. Do it the hard way. Sigh. It takes a little self-discipline to save things in SSMS tabs in lieu of just closing the tabs. Whew! This a better way to write SQL than just in Notepad where RedGate can't assist you with IntelliSense.