Nate I meant a version of the JSON export, not Spine itself. Like, will the data of the movement will be exported to a code correctly in a lower version? For example my game engine support 4.0 export, but I work in 4.2, everything works correctly except sequences.
The Spine 4.3 beta has begun
You can find a more comprehensive response in Nate's replies here.
Davide Thank you. That answers my question.
新版变化约束个人使用之后，感觉可以增强使用体感的方面
1.属性之间的链接，能否像骨骼显示一样，可以往下拖动链接。目前鼠标左键右键都是连线，可以把其中一个改成往下拖到链接，对于想要链接所有属性的操作，会更便捷。
2.从左边属性链接到到右边，已有属性能否允许链接，然后原有的自动断开。目前链接已链接好的属性，必须先断开，再重新链接，有些繁琐。
3.这个链接的面板能否固定住，不乱动。链接面板有点小，当下面出现或消失新的熟悉的时候，他会上下跑，链接面板本来就小，属性的链接点更小，再乱跑的话，比较难选取。
以上是个人对新版变换约束的一些体验感觉。
Thank you for this very important feature. I've been waiting for something like this for a long time, and it's really going to make Spine so much more powerful. My question is, does anyone know the schedule for the Runtime updates to support the 4.3 features?
We've already started porting this feature to some runtimes (ts based runtimes and Unity) on the beta branch, but we haven't released them yet.
Which runtime are you using? If it's one of the above, you could build it from source, but be aware that the beta branch may contain bugs, and some fixes might not be ported yet.
It's a lot of fun!
It reminds me of a lot of fun settings with new features!
Thank you!
In the generation of the name of the constraint, could you please add '_' instead of Spacebar?
Spacing is very careful in programming.
Davide We're using the latest Unity runtimes. I'm not sure we're allowed to use Beta runtimes, but it's nice to know that we could at least test it out. I'm glad to hear that the Unity runtime update is close. This is going to be fantastic! Thank you again for the info.
Cool videos! There's a cat behind the door! 
Constraint names are strings and don't affect code. The issue with space is that it can't be seen and is relatively narrow. In a textual context it's uncommon to write nametoother without spaces (at least in English), but I can appreciate avoiding spaces in names to maximize clarity. However, I am not a fan of underscore. We could use hyphen -.
This so far has felt really fantastic to use, great job guys! The amount of doors that this opens already is really incredible, it's hard to think about just how useful this will be!
Not sure if it's been suggested already but given that, abstractly - the UI (and presumably the underlying implementation in the runtime) that's been built for this maps from one value range to another + the ability to clamp on either end, it would be incredible to have the ability to map any of these properties in the same manner but to the color channels / opacity on a set of slots.
Not necessarily on the transform constraint itself - maybe a separate constraint? dunno!
Same UI but with source being a bone with targets being a set of slots, and the same source properties Rotation, Translate X, etc.. just mapping to the targets H/S/V/R/G/B/A channels separately with the same Options as well.
Just my two cents from fiddling around with this for the past couple days - the power that I gain with these transform constraints makes me giddy, but I then get put down at needing to run back and manually key opacity/color changes for the otherwise totally automated bits of some of the rigs I've been fiddling with. In my eyes that's the biggest missing link to having a really powerful suite of tools to build out controllers to manage complex transitions between poses and a huge variety of other things!
yugutou Thanks for the feedback. Please try 4.3.14-beta, we've improved some of the areas you mentioned. We moved properties to the bottom, so they don't jump around.
We considered replacing existing connections when dragging a new connection, but it would only work on the right side and there is some worry it would be easy to accidentally replace a connection.
Dragging like in the tree is interesting. It's a little tricky, as we already have a drag operation for making connections, so we'd be dual purposing drag. Eg, you could drag down to create straight across connections, then drag to the right to make a connection. That makes it complex to implement. I wonder how often you really need all 6 properties mapped? It's more efficient to map fewer properties.
lightluxio Glad you like it! We have a solution in mind for mapping to slot color, attachment changes, and anything else that can be keyed. We should be showing it off soon!
Nate Crazy exciting! Absolutely can't wait!
你好，关于变换约束的连线提个建议。
1.在“设置”界面的连线上显示百分比，但在“动画”界面里的连线上没有显示百分比。见下面的截图。
2.这个连线上的百分比数字能否始终显示，鼠标悬停不够方便，也无法同时查看多条连线的比值。但这也会造成个问题，在多条连线交叉的情况下显示有些混乱。
Hi, long time no see! Working on a new game and these are great for characters I'm rigging up. We are currently using runtime 4.2 in Unity. How long would you GUESS it might be before there's a 4.3 runtime? Also, if I export from Spine 4.3 to use in unity runtime 4.2, will it break, or is there some back compatibility? Would love to use these features! Thanks
mogbot We are currently using runtime 4.2 in Unity. How long would you GUESS it might be before there's a 4.3 runtime?
No need to guess, the 4.3-beta spine-unity runtime is already available.
https://esotericsoftware.com/spine-unity-download#spine-unity-4.3-beta
There has also been an update yesterday which makes it compatible with exports from Spine 4.3.14-beta again (which changed the export format).
mogbot Also, if I export from Spine 4.3 to use in unity runtime 4.2, will it break, or is there some back compatibility?
If you mean exporting from editor version 4.3-beta and importing in editor version 4.2: Features which are available in 4.3 and not in 4.2 will break.
Wow, this is the feature I've been waiting for and looking forward to 
I think it's becoming a huge tool with no real replacements
Are you considering color change and image replacement as constraints??
If this is possible, I think I can make much more interesting things.
Really a big game changer. Trying on couple cases and It's really useful. Especially on creating control rigs or connected bone structures other than IK
I was thinking about how to visually show some of the 'clamps' or limits because often the constraints becomes kinda trial and error to get the right values (oh, the control is rotated 90 degrees so translate X (left right) becomes Y (up down) etc).
Something like this (the yellow line/box) would be super useful especially for setting up control rigs. They do this in things like blender etc.
^ A little checkbox by the clamps.
^ Translate X clamps shown visually in the viewport (with yellow line)
^ Translate X and Y clamps shown visually in the viewport (with yellow square).
Somehow showing a 'ghost' of what the effect would be on the resulting bone would also be incredible. Maybe as you roll over each constraint value it would show the min/max result in the viewport as a ghost.
PS.Would also LOVE alpha/constraints (ie rotation or translation to control opacity). Would be incredibly useful for asset swaps like hand poses. So happy to see someone else suggest that and that it's something you are looking at!