zhihai,
You are correct in the All-In-One we don’t ship the PDE (something we may change going forward).
You should be able to install it by using the Update Mangaer with the 2nd option “Find and install new features” then using the Callisto Discovery site. From there you should be able to install the PDE.
And easier way might be to include both the Mylar and Discovery sites in your “Search for new features” run, then select Mylar and hit the dependencies button on the right that will select all missing dependencies for Mylar automatically.