Reviving Old X Code

The problem is that a lot of software... disregarded the specs. Including infamously using "reserved for future use" areas of bitfields, which for example caused a lot of app crashes during early days of Windows 95 (where certain common API gained a new flag that was not compatible with previous flags, which worked fine so long as you didn't set them concurrently - which all properly written applications avoided.)

That's not really true though, there are some real differences between copyright laws in different countries:

* US copyright law appears to recognise the ability of a copyright owner to relinquish their copyright to the public domain pre-expiration, German copyright law denies them that ability

* US copyright law has the concept of fair use; Australian copyright law lacks the concept of fair use, although it does have the significantly narrower concept of fair dealing

* Most EU countries recognise the concept of "moral rights of the author" in their copyright law, US copyright law generally speaking does not (it does for copyright on visual arts works under The Visual Artists Rights Act of 1990, but not in general)

* EU has the concept of a database right, which protects the contents of a database from copying even if the work of assembling was mere "sweat of the brow" involving no originality; the US does not, and mere "sweat of the brow" does not meet the copyright standard in the US (see Feist vs Rural Telephone Service Co)

* US law says that accurate photo-reproductions of public domain 2D works are themselves public domain – see Bridgeman Art Library v. Corel Corp – there is no independent copyright in the photo since there is no originality involved (selection of camera angles etc), and mere "sweat of the brow" is not enough for a copyright to exist. It appears – although not completely settled – that UK law, by contrast, has a weaker threshold of originality, such that mere "sweat of the brow" is enough. This was the crux of the dispute between the UK National Portrait Gallery and Wikipedia. Since it never went to court, we can't know for sure what the UK law actually is on this topic

* UK law provides special protection to specific works. For example, even though Peter Pan is out of copyright, there is special legislation requiring commercial productions based on certain Peter Pan works to pay royalties. Likewise, there used to be an "eternal copyright" on the King James Bible and Book of Common Prayer – that "eternal copyright" has been abolished, but still applies by a grandfather clause until the late 2030s. By contrast, the idea of specific works being legislated special IP protection is rather unheard of in the US (outside of trademark law, wherein the US does it too)

There's a lot more fiddly little differences. The Berne Convention, WIPO, TRIPS, etc only mandate the broad outlines of IP law, the fine details are up to each country and different countries do different things. Every country has its own statute law and case law and differences inevitably emerge

I'm not sure where you heard this, but it's not correct, you might consider checking the extension spec and the implementation in the server:

https://www.x.org/releases/X11R7.7/doc/renderproto/renderpro...

https://gitlab.freedesktop.org/xorg/xserver/-/blob/master/re...

The reason why it's not used in all cases is because it doesn't map 1:1 to cairo and there are things missing, e.g. curves probably being the most important. You would have to ask Keith for a definitive answer why this is since he wrote both XRender and Cairo. (I assume it's because Cairo already included the necessary tessellation steps at the time)

Indirect GLX does work great for simple use cases, once you start to add textures into the equation the amount of bandwidth used would probably make it unusable over the network. There has been no serious work in getting indirect GLX working past OpenGL 1.x. I think another one of the main problems is that nobody really came up with a good way for GL extensions to work well there, the server needs to manually add an implementation for every extension you want to use.