Aka the use of private Windows API’s by IE was explicitly banned in the decent decree.

The initial case which MS lost would have resulted in splitting the company, on appeal and by the time of the new trial (which they also lost) the government changed its mind into no longer seeking to break up the company. But that was on the government not a legal victory by Microsoft.

> However, the DOJ did not require Microsoft to change any of its code nor did it prevent Microsoft from tying other software with Windows in the future

“H. Starting at the earlier of the release of Service Pack 1 for Windows XP or 12 months after the submission of this Final Judgment to the Court, Microsoft shall:

1. Allow end users (via a mechanism readily accessible from the desktop or Start menu such as an Add/Remove icon) and OEMs (via standard preinstallation kits) to enable or remove access to each Microsoft Middleware Product or Non-Microsoft Middleware Product by (a) displaying or removing icons, shortcuts, or menu entries on the desktop or Start menu, or anywhere else in a Windows Operating System Product where”

https://www.federalregister.gov/documents/2001/11/28/01-2949...

the only way to achieve the above is to change windows code.

The API issue wasn’t one of code it was one of documentation:

“The proposed settlement required Microsoft to share its application programming interfaces with third-party companies and appoint a panel of three people who would have full access to Microsoft's systems, records, and source code for five years in order to ensure compliance.[28]” https://en.wikipedia.org/wiki/United_States_v._Microsoft_Cor....

It publishing API’s may seem like a strange remedy but it was a common tactic they used to limit competition. Netscape for example couldn’t release Netscape for Windows 95 at release because while the IE tea, had access to API’s they weren’t providing them publicly until release.