While testing #8242 I noticed a couple of usability issues when saving an entity. - Eg when going to "Admin => General settings" and clicking "Save" (or Sites Management add/edit site or Users Management edit user) it could be nice to change the "state" of the button and use a wording like "Saving" and making the button disabled while the saving is in progress. We recently changed this in the Core Updater as one didn't know whether it is actually doing something or not. It was not really a big issue before as the requests were sync and one couldn't do anything while they were in progress - When clicking "Save" in "Admin => Plugin settings" it shows "Loading data..." above the "Save" button for a short time. When deleting a user it shows "Loading data..." for a short time as well. Also when pressing "Save" in Personal Settings.
Goal is to have a consistent behaviour re "Saving", "Deleting", ... across Piwik: - We should not show any "Loading data..." when saving/deleting an entity - We should show eg "Saving" as button text while a request is in process - We should deactivate the button once XHR is active so one cannot press it two times