Today, nearly every extension and addon in Mozilla Firefox got disabled due to an expired certificate that was used to sign these extensions / addons.
To fix this, go to about:config and search for xpinstall.signatures.required. Set it to false, then remove and re-add your addons.
In 2017, with the release of Delphi 10.2 Tokyo, Embarcadero introduced a specialized implementation of the Observer pattern into the System.Classes unit. While it has been in the wild for 9 years, it remains a "hidden" architecture for many, primarily because it serves as the invisible engine behind LiveBindings. Other than live bindings, you can also use the Observer pattern as a way to update component settings to the Windows registry, an .ini file, or persist it elsewhere.
System.Classes