When the notification server callback is executed by the Windows
notification system, it invokes Firefox with additional command line
parameters, most importantly the Windows-specific notification
"Windows tag".
If no appropriate Firefox is running, the command line will be
processed, the provided Windows tag will be inspected (and seen to not
be registered with this running Firefox instance) and a "launch URL"
stored as part of the Windows notification itself opened (if one is
provided).
If an appropriate Firefox is running, the remoting protocol will
forward this command line to the running instance. If the instance
recognizes the provided `--notification-windowsTag`, the command line
will be ignored. When the notification server exits, Windows will
fallback to the Windows 8.1 style notification callbacks registered
for this Windows tag and the existing (non notification server)
behaviour will occur.
In fact, the server therefore waits for a Windows tag-specific system
event to be signalled by the invoked Firefox (or a sibling process).
If we were to return `S_OK` from the notification server immediately,
and a running Firefox process would handle the notification via
Windows 8.1-style notification callbacks, then Windows would fall back
to those callbacks. The invoked callbacks unregister themselves upon
completion, often before the launched Firefox has an opportunity to
process the command line. By waiting for this system event, we allow
the invoked Firefox to process the command line while its own
notification callbacks are registered and therefore recognize that its
callbacks will handle the notification.
Differential Revision: https://phabricator.services.mozilla.com/D154468
An explanation of the Firefox Source Code Directory Structure and links to
project pages with documentation can be found at:
https://firefox-source-docs.mozilla.org/contributing/directory_structure.html
For information on how to build Firefox from the source code and create the patch see:
https://firefox-source-docs.mozilla.org/contributing/contribution_quickref.html
If you have a question about developing Firefox, and can't find the solution
on https://firefox-source-docs.mozilla.org/, you can try asking your question on Matrix at chat.mozilla.org in `Introduction` (https://chat.mozilla.org/#/room/#introduction:mozilla.org) channel.
Nightly development builds can be downloaded from:
https://archive.mozilla.org/pub/firefox/nightly/latest-mozilla-central/
- or -
https://www.mozilla.org/firefox/channel/desktop/#nightly
Keep in mind that nightly builds, which are used by Firefox developers for
testing, may be buggy.
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