**System Information**
Ubuntu 14.04 64 bit
**Blender Version**
Broken: Blender 2.76 RC1
**Short description of error**
I can't use weigh paint x mirror if using Weght tools like levels or weight gradients (alt-left click or ctrl-alt-left click).
**Exact steps for others to reproduce the error**
Create a symetrical geometry.
Go into weight paint mode.
Turn on X mirror.
Try to use some tools in Weight tools (levels, or weight gradients).