System Information
Operating system and graphics card
OSX 10.11.6
AMD FirePro D700
Blender Version
Broken:2.78a (e8922c8)
Worked: 2.77a
Short description of error
When weght painting, Show Zero Weights doesn't work.
It should show black faces where there are 0 weight when it's set to Active, but it shows blue faces.
Exact steps for others to reproduce the error
Weight paint any mesh and set Show Zero Weights to Active.