[gens]

Screen tearing under X11 is more or less not a problem anymore. HIDPI, yes, but only for multiple monitors (maybe even just programs that don't support it properly ?). Security... eh, yes and no (Xorg can be ran as a normal user).

The actual good thing about Wayland is that it simplifies things. While the bad thing is that it needs some kind of extensions for even the basic things a desktop needs, and that (AFAIK) freeGNOMEdesktop is in charge now.

[pengaru]

> Screen tearing under X11 is more or less not a problem anymore.

For GLX/DRI clients where there's an actual concept of swapping buffers w/vsync, sure, but for classical X clients this is not true.

X got extensions for double buffering at one point, but practically nobody uses them.

There is no concept of a "completed frame ready for presentation" in core X, there's no way to really fix this without ceasing to be X (hello, Wayland). X compositors literally just drain event queues of X requests and throw shit on-screen when the event loop gets around to it. If that presents a partially updated window, so be it. GTK+/GNOME folks added "frame clocks" to try work around it, but not everything is a modern-ish GTK+ app, nor do all compositors implement it.

If there's anything Wayland fixes that really required such an upheaval to fix, it's flicker/tear-free compositing.

[gens]

Well, it seems to work fine (xorg.conf tearfree option, that is). AFAIK wayland compositing also has the problem that clients don't know when they should be done with rendering, as in when the flip is going to happen. I don't know much about how it (wayland, DRI) actually works (as in, can the "client" just render where the compositor told DRI it should without involving the compositor, or does it have to tell the compositor when it rendered).

GNOME3 had(has?) many a timing problems.