If you're making a program today, you should be using some higher level framework or API than raw X11. If you program for Gtk or Qt, or make an OpenGL or Vulkan program, you mostly don't care about X11 or Wayland because i.e. Qt supports both.

You could use Xlib to program a client in pure X11, but that approach would have been outdated even 15 years ago. There's no good reason to do so today, even embedded systems often use Qt and there's good support for building embedded/Qt in Yocto. Most embedded devices that have any UI at all are likely powerful enough to run Qt, so I suspect there aren't many cases these days where you need to limit yourself to Xlib because of performance.

> You could use Xlib to program a client in pure X11

Xlib is actually not very pure X11; Xlib makes a lot of things synchronous whereas X11 is really an asynchronous messaging distributed systems protocol that happens to output to the screen as a side effect. Xcb is a much closer to the actual protocol library.

IMHO, a lot of early hate for X11 was really hate at Xlib; but as Xlib was the official library, it was understandable to get them confused.

XCB is missing support for some important extensions, though. Such as Xft, so you can't display modern anti-aliased fonts (unless you somehow use Xlib at the same as XCB, I think?).

Tje Xft library is all about rendering the fonts on client side - it does use the Render extension but that's supported by xcb.

Ah, I guess I was thinking of libxft. There doesn't seem to be an equivalent for XCB, so you'd have to connect all the parts on your own.

Recently I ported a xlib game to SDL. Another option to add to that list.

Whatever comes after X11 will also go away, probably before X11 has actually gone away.

After X11 shall come X12. But, as the song says, we are living on a planet that's revolving and evolving...

X11 is not going away explicitly, but, Just... Afaik maintaining it is huge pain.

Things are slowly shifting to Wayland.

I suspect Wayland will be as ipv6.

Never fully used by all, old hardware around for decades without it, and likely require something else, such as X11 now supports wayland!

Just as I suspect ipv8 will make ipv6 disappear!

ipv8 is identical to ipv4, it just has another 256 in front of it. 5 octlets. A 6th octlet for planet designation...

Wayland looks like the impaired child of X. They promise some security and they are reinventing the wheel.

X11 is becoming a legend in both good and bad sense.

OpenGL [0], or Gtk/Qt based frameworks basically.

Very few would bother to do X11 graphics directly with Xlib, we aren't in the 1980's.

[0] - Some would say Vulkan I rather spare myself the burden.

It will go away in '22.

2122 of course.

Except for a colony planet of Modern Amish, which refuse to embrace brain implants, age extension tech, and X11 replacements.

X11 forever!