Ok. After a short debate and experimentation with Mercados ideas, here it is:
https://stash.reaper.fm/oldsb/126275/...6-commands.zip
You need both
Xenakios' extension and
SWS' extension.
Snap Left Edge of Item under mouse cursor to Edit Cursor
Snap Right Edge of Item under mouse cursor to Edit Cursor
Snap Left Edge of a COPY of the Item under mouse cursor to Edit Cursor
Snap Right Edge of a COPY of the Item under mouse cursor to Edit Cursor
Snap Item's Snap-Offset(Syncpoint) under mouse cursor to Edit cursor
Snap an Itemcopies's Snap-Offset(Syncpoint) under mouse cursor to Edit cursor
Cockos, this doesn't let you off the hook either. This really ought to be included in the standard distribution of Reaper. Editors of all camps will thank you for it.
Please keep in mind that all automation has to come along with items or their copies. Native implementations of these commands may be the only safe solution to ensure this.