Windows 8.1
Nvidia Geforce 980m

Blender Version
2.77

Short description of error
I work with a rig, but when i try to paint weight with the Weight Paint tool, ans select the "Face selection masking for painting" it won't let my paint.
And Without this, I can't see the lines

Exact steps for others to reproduce the error
rig a caracter, go to Weight Paint, click on the Face selection masking for painting options and try to paint weight on the mesh.
it don't work for me