Most (all?) of the project capabilities are based on open source projects. So it is possible to download the source and attach it to the project, but that takes a fair amount of effort. One has to figure out exactly which version is used in the current version of ME, then find that version of the source, download it, and attach it. In some case ME includes bug fixes so the exact source is not available from the obvious place. Including all the sources with the ME install is probably a bad idea since most users would only ever look at a tiny fraction of the source.
A better solution would be a One-Click source install. ME knows the exact version was used to create each project capability. It should be fairly easy to have an “Install Source” button in the “Project Capabilities” preference dialog that will download and attach the source for the selected project capability. If ME is upgraded it should be able to upgrade the installed sources as well (nice to have).
Douglas