**System Information**
Operating system: Linux (and others)
Graphics card: nVidia 1060
**Blender Version**
Broken: 2.9x
**Short description of error**
In Weight Paint mode:
If I lock some vertex groups and then Weights -> Smooth (or any operation that has adjustable values), things behave as expected. BUT, if I then try to alter the values the Properties popup window, the list of locked vertex groups changes (revert/undo?), which causes weights to bleed undesirably & defeating the purpose of locking groups.
This can sometimes even return a "All groups are locked" error,BUT, if I then try to alter the values the Properties popup window, the list of locked vertex groups changes (revert/undo?), which causes weights to bleed undesirably & defeating the purpose of locking groups.
This can even return a "//All groups are locked//" error, if the previous configuration had 1 or less groups unlocked and Weights -> Normalize All is performed. if the previous configuration had 1 or lessNormalize All needs at least 2 groups unlocked and Weights -> Normalize All is performedto shift weights around, as Normalize All needs at least 2 groups unlocked to shift weights around and if you try to alter the properties popup it will revert the locked weights list to an incompatible configuration.
I've testverified this bug with the Smooth, Levels and Normalize All procedures, and all reveal the bug. So. Therefore, I'm assuming this will affect any Weights operation that has an adjustable properties popup.
**Exact steps for others to reproduce the error**
1. Create cylinder (subdivisions not needed, but helps if you wan to understand the technique being used).
2. Skin cylinder to chain of at least 3 bones that resides within the cylinder.
3. Enter Weight Painting mode.
4. Lock all but 2 of the vertex groups, and select one of the unlocked groups.
5. Activate Weights -> Smooth
6. Adjust some values on the Factor or Iterations on the Properties popup.
7. Notice how the list of locked groups changes.
{F9532295}
**Assumed Issue**
Perhaps Blender is altering these Properties values via Undos?
If, in between steps 4 and 5, you perform another action (i.e. enter and exit Edit mode) it will not change the list of locked Vertex Groups.
**Importance**
This weight locking technique is very effective in preventing skin weights from bleeding across the model when skinning, causing messeswhich creates a mess that require cleanup (*see timestamp 9:30 Demeter's tutorial on "[[ https://cloud.blender.org/training/weight-painting/5efe0d7405aef1cf3b89644d#comment-4576 | Weight Painting Part 2 ]]". Demeter demonstrates the problem and his workaround, at 9:30 where he demonstrates thewhich can introduces other problem and his workarounds, which introduces other problems. as the "Clean" operation is destructive and does not always fully fix the bleeding weights.
In the comments of the tutorial, I demonstrate the precision of the lockgained when using weights techniquelocked group weights and how it prevents bleeding, thus preventremoving the need of the destructive "Cfor any post clean" operationup.
This bug prevents the awesome property sliders from being used, meaning that values have to be set very low and the weighting operation needs to be performed in multiple steps till the desired effect is reached. This is not a very effective workaround.