I inadvertently accepted android studio's upgrade suggestion to 2.3 (canary), although I had always had it set to check for the developer channel, not canary, somehow that got switched. Now I no longer have a 'Launch Standalone SDK Manager' option in my 'SDK Manager' window.
I liked the standalone manager for various reasons, including that it suggested what needed to be downloaded and upgraded. The regular sdk manager lists a lot of things I expect I don't need like 'CMake', 'LLDB', 'Constraint Layout for Android', 'Solver for ConstraintLayout', 'Google Play APK Expansion Library' ('Google Play APK Expansion Library rev 3' is already installed, so do I need this too?), etc.
Is the standalone sdk manager unavailable for 2.3 canary 2, or is there something more I need to do to get it?
I also have updated to the Canary version 2.3 and I'm amazed that they took it away there.. but you can still start it via the SDK Manager.exe
located in your sdk folder
C:\Users\You\AppData\Local\Android\sdk