Gtk 3->4 made a lot of internal changes, and at least some were related to making wayland work.
Wayland “worked” in gtk3, however it was very much an afterthought, and half the toolkit was useless under wayland.
Other changes are usually required for changes related to rendering, gtk4 had vulcan rendering which may require some breaking changes.
Another thing is just general breaking changes that are good, sometimes you realise some decision was bad, and a new major release is just a way to make these.
From the end users perspective nothing much changes, it maybe looks a bit different, but not much besides that. But a vulcan renderer and being fully wayland compatible are major improvements that also improve the user experience, even if you don’t notice directly.
Usually the problem isn’t that the changes are big, but that the new way simply isn’t compatible with the old way to do things, and you can’t just make a change that will break existing applications in minor versions (well, there’s nothing technically stopping you, and unintentional compatibility breaking bugs have definitely happened in the past, but people are gonna get real mad at you if you do that). Even if you break that change up into thousand tiny changes over many minor versions, the end result is that at some point, you break old apps.
The solution is to take note of all the things that are either badly designed or became obsolete and once in a while go “hey, let’s make a new major version and fix all of this crap”. With a new major version, you don’t have to worry about old applications and are free to improve your library in any way you wish, and you also get the option to keep updating the old major version with some maintenance bugfixes so that the old apps keep working well enough.
Gtk 3->4 made a lot of internal changes, and at least some were related to making wayland work. Wayland “worked” in gtk3, however it was very much an afterthought, and half the toolkit was useless under wayland. Other changes are usually required for changes related to rendering, gtk4 had vulcan rendering which may require some breaking changes. Another thing is just general breaking changes that are good, sometimes you realise some decision was bad, and a new major release is just a way to make these.
From the end users perspective nothing much changes, it maybe looks a bit different, but not much besides that. But a vulcan renderer and being fully wayland compatible are major improvements that also improve the user experience, even if you don’t notice directly.
Interesting. I’m guessing the changes were too big to just be added incrementally in updates to GTK 3?
Usually the problem isn’t that the changes are big, but that the new way simply isn’t compatible with the old way to do things, and you can’t just make a change that will break existing applications in minor versions (well, there’s nothing technically stopping you, and unintentional compatibility breaking bugs have definitely happened in the past, but people are gonna get real mad at you if you do that). Even if you break that change up into thousand tiny changes over many minor versions, the end result is that at some point, you break old apps.
The solution is to take note of all the things that are either badly designed or became obsolete and once in a while go “hey, let’s make a new major version and fix all of this crap”. With a new major version, you don’t have to worry about old applications and are free to improve your library in any way you wish, and you also get the option to keep updating the old major version with some maintenance bugfixes so that the old apps keep working well enough.
The unfortunate consequence of this is that old working apps need compatibility updates.