Site validation has been tightened. Previously, only the language code and project name had to be valid - now, they must be a valid combination (i.e. en.wikiversity exists, and so is valid, but sco.wikiversity is not valid, because no such wiki exists).
When the global watchlist feed is loading, an OOUI widget will be shown, rather than an animated gif.
An option has been added to no longer group edits to the same page. For now, this isn't very useful, since metadata for the edits (editor, summary, tags, etc.) are not yet shown, but they will be soon. Until then, ungrouped edits are treated the same as pages with only 1 edit - the minor and bot flags are displayed if applicable. If edits are grouped, the minor and bot flags are only shown if they apply to all of the edits.
Starting with version 5.0, there will be an option at the settings page to switch to and from a "stable" version of the script. When activated, the script import in your global.js should be replaced, and then the page refreshed with the new script loaded. The stable script will live at User:DannyS712/Global watchlist/stable.js, and will be updated with each full release. Otherwise, it shouldn't be edited, providing a version that is less prone to bugs as the script is developed.
WARNING: Starting with version 5.1, the option to mark the pages of a site as seen be implemented using the entirewatchlist API option, rather than manually listing the titles. This is being done to simplify the implementation code. This will result in the same functionality as marking all pages as seen via Special:Watchlist (i.e. even if the page isn't visible due to your filter choices, it will still be marked as seen). If you would like to keep using the current method for a while, please switch to the stable branch.
Version 5.0 has just gone live. It includes the new features mentioned above.
I am investigating adding more context to each entry that is shown (such as the edit summaries, tags, patrol marks, the user who made the edit, etc.). Is there any desire for such additions? If so, what should be added first, and what is a low priority? Please leave feedback on the relevant phabricator task, phab:T238300.
Site validation has been overhauled. Rather than hard-coding a list of valid sites, users will be able to watch any site where they have an attached local user account. If a site is rejected as invalid, please ensure that there is indeed a local account attached to your global account.
Users will now be alerted regarding the results of attempting to update their settings.
Live updates have been added - when activated, the script will refresh in the background, and then load the new feed, every 7.5 seconds. In the future, this frequency may be configurable.
OOUI icons have been added to most buttons.
There is now an option to eliminate the confirmation dialog when marking all sites as seen.
WARNING: Starting with version 6.1, site aliases currently used when saving settings will be removed, and only sites in the form of `lang.project` will be accepted.
As noted in the last update, marking a site as seen now uses entirewatchlist, which means that any changes to watched pages between when the watchlist was loaded and when the site was "marked as seen" may be ignored.
Version 6.0 was just finalized for the development and stable branches of the script.
A new "fast" mode has been introduced. When used, the watchlist serves as just a list of pages that have been modified, and no longer includes context about the edits themselves.
More information has been added to entries. When edits are not grouped by page, or when there is only 1 edit to a page, minor and bot flags are shown, as well as the user who made the edit, the summary used, and any tags that were applied. When multiple entries are grouped, bot and minor flags are only shown if all of the grouped edits were made by bots or where marked as minor. If only 1 user edited the page, that user's name is still shown, but no summaries or tags are included.
All watchlists are now fetched in parallel, rather than in series, greatly reducing load time.
Most of the source code is now annotated with jsdoc notes, allowing others to more clearly understand and review the code.
I will be looking into creating guidelines to let others contribute to the script; see phab:T238298.