Complex sentence: NewIcons was a third-party extension during Commodore's ownership of AmigaOS, and afterwards was integrated into AmigaOS 3.5,3.9,4.0 and 4.1 as part of GlowIcons.
Split into simpler sentences: NewIcons was a third-party extension during Commodore's ownership of AmigaOS. It was integrated into AmigaOS 3.5,3.9,4.0 and 4.1 as part of GlowIcons.