[imtringued]

This patch in particular is about implementation differences between Microsoft's XML implementation and libxml2 and the emulation of Internet Explorer quirks. [0], [1]

>And how much of it is simply better emulating the Windows API in general?

It depends on your definition of "Windows API". If you think Internet Explorer is part of the "Windows API", then this patch is 100% about better emulating the "Windows API".

>How much of these sorts of patches are specifically checking if a certain application is running, and then changing behavior to match what that application expects?

Probably near zero, because there is not much point in doing so. If you need to get a specific application to run on Wine that doesn't work out of the box, you're expected to follow an application specific recipe (installing particular versions of Windows libraries or selecting the version of Windows to be compatible with) rather than Wine itself special casing application support. There were plenty of ways to get Photoshop running on Wine in the past, the practical problem was that they were too reliant on already having a full Windows installation, which defeats the point of using Wine.

[0] https://github.com/PhialsBasement/wine-adobe-installers/comm...

[1] https://gitlab.winehq.org/wine/wine-staging/-/commit/8090aa9...