but that is not about IE4

I see. Although filters were implemented in IE4, DirectX filters came about in IE5.5

However, the extend phase wasn't just IE4. They stopped piling on all sorts of non-standard vendor lock-in stuff after IE6. By the time IE7 came out, it was clear the web is here to stay.

	▲	duskwuff 14 minutes ago \| parent [-]
		> They stopped piling on all sorts of non-standard vendor lock-in stuff after IE6. IE6 also stuck around a lot longer than previous versions. It was released in 2001; IE7 didn't show up until 2006, and was an optional update which many users skipped.