Page editing instrumentation

This is a Bucket list of some areas (in the action=edit?) around which we need data to make some design decisions.

Click tracking

 * Preview
 * Show Changes
 * Marking as a minor edit
 * Move

Click tracking + content analysis

 * Edit Summaries (How many users provide edit summaries)

Disclaimer
Any data from simple action tracking will lack rigor &mdash; it's a precursor to an experiment, not a valid experiment with testable hypotheses.

Possible design

 * upon [Save page] / [Show preview] / [Show changes] record the click action (using Extension:E3 Experiments' event tracking built on Extension:ClickTracking, as used on Community Portal)
 * include
 * whether "This is a minor edit?" is checked or not
 * the length of the edit Summary text, hence 0 means no summary provided or the edit Summary text itself (see )

Data Format
Format is

Questions

 * Do we really want to track each click to check and uncheck "This is a minor edit?" Or just record it as part of the [Save page] / [Show preview] / [Show changes] event logging?
 * A: The latter. We store it as a form submit events
 * Can we check to see if the summary text was changed from the suggested defaults? Like, there's defaults when you undo or rollback.
 * A: Maybe... on load look at input#wpSummary.mw-summary, remember contents, upon submit see if the contents have changed from e.g. "Undid revision 507859909 by ...". Problem is, on save after preview or show changes, the initial contents will be what the user entered last time. Maybe include the text of the summary (limited to 255 in the HTML form) in the click action, and let later post-processing figure out if it's a stock message. For now, we just store the wpSummary text; analysis is left as "a simple exercise for the reader".