I seem to remember reading in an old paper (1990s?) that the asynchronous nature of the connection between the X server and the window manager results in essentially unfixable protocol-level races.

Maybe this one [1] from 1987? It says:

> There are many race conditions that must be dealt with in input and window management because of the asynchronous nature of event handling. [...] However, not all race conditions have acceptable solutions within the current X design. For a general solution it must be possible for the manager to synchronize operations explicitly with event processing in the server. For example, a manager might specify that, at the press of a button, event processing in the server should cease until an explicit acknowledgment is received from the manager.

[1] https://web.mit.edu/6.033/2006/wwwdocs/papers/protected/xwin...

Wayland has a philosophy of "every frame is perfect", which means fixing every race condition. However, X11 doesn't have this philosophy. If the window manager is slow and doesn't respond to a notification that a window has been resized, drawing the new window content over the old borders is the correct thing to do. What sense does it make to freeze the whole display just for a window border?

Similarly, tearing gets pixels to the screen faster.

I covered that in the X-Windows Disaster chapter of the Unix Haters handbook, and many HN posts, and other articles. So it's quite disappointing and underwhelming that Wayland failed to learn or apply any of these lessons. All this stuff was widely discussed long before Wayland was designed in reaction to X11, without considering any alternatives than Windows and Mac.

https://donhopkins.medium.com/the-x-windows-disaster-128d398...

https://news.ycombinator.com/item?id=22491561

https://news.ycombinator.com/item?id=15035419

https://news.ycombinator.com/item?id=28522534

https://news.ycombinator.com/item?id=44045304

https://news.ycombinator.com/item?id=29964737

https://news.ycombinator.com/item?id=15327339

https://www.donhopkins.com/home/catalog/unix-haters/x-window...

https://blog.dshr.org/2024/07/x-window-system-at-40.html

David Rosenthal wrote:

>There is a certain justice in The UNIX-HATERS Handbook's description of my efforts:

Ice Cube: The Lethal Weapon

One of the fundamental design goals of X was to separate the window manager from the window server. “Mechanism, not policy” was the mantra. That is, the X server provided a mechanism for drawing on the screen and managing windows, but did not implement a particular policy for human-computer interaction. While this might have seemed like a good idea at the time (especially if you are in a research community, experimenting with different approaches for solving the human-computer interaction problem), it can create a veritable user interface Tower of Babel.

If you sit down at a friend’s Macintosh, with its single mouse button, you can use it with no problems. If you sit down at a friend’s Windows box, with two buttons, you can use it, again with no problems. But just try making sense of a friend’s X terminal: three buttons, each one programmed a different way to perform a different function on each different day of the week — and that’s before you consider combinations like control-left-button, shift-right-button, control-shift-meta-middle-button, and so on. Things are not much better from the programmer’s point of view.

As a result, one of the most amazing pieces of literature to come out of the X Consortium is the “Inter Client Communication Conventions Manual,” more fondly known as the “ICCCM”, “Ice Cubed,” or “I39L” (short for “I, 39 letters, L”). It describes protocols that X clients must use to communicate with each other via the X server, including diverse topics like window management, selections, keyboard and colormap focus, and session management. In short, it tries to cover everything the X designers forgot and tries to fix everything they got wrong. But it was too late — by the time ICCCM was published, people were already writing window managers and toolkits, so each new version of the ICCCM was forced to bend over backwards to be backward compatible with the mistakes of the past.

The ICCCM is unbelievably dense, it must be followed to the last letter, and it still doesn’t work. ICCCM compliance is one of the most complex ordeals of implementing X toolkits, window managers, and even simple applications. It’s so difficult, that many of the benefits just aren’t worth the hassle of compliance. And when one program doesn’t comply, it screws up other programs. This is the reason cut-and-paste never works properly with X (unless you are cutting and pasting straight ASCII text), drag-and-drop locks up the system, colormaps flash wildly and are never installed at the right time, keyboard focus lags behind the cursor, keys go to the wrong window, and deleting a popup window can quit the whole application. If you want to write an interoperable ICCCM compliant application, you have to crossbar test it with every other application, and with all possible window managers, and then plead with the vendors to fix their problems in the next release.

In summary, ICCCM is a technological disaster: a toxic waste dump of broken protocols, backward compatibility nightmares, complex nonsolutions to obsolete nonproblems, a twisted mass of scabs and scar tissue intended to cover up the moral and intellectual depravity of the industry’s standard naked emperor.

Your memory is insanely impressive to remember such an obscure article from so long ago.