Bug 477921

SUMMARY
When Ⅰ slide the size of brushes that named ‘‘mypaint’’，once I release the pen，the number jumps to  the original number.
for example，now the size of "pencil 2b(mypaint)" is 2，then I slide it to 10. When i release the pen，it jumps to 2. But when i draw by this brush，the size is 10 in reality，though it shows "2".
When i turn to the previous old version，the bug doesn't exist.

STEPS TO REPRODUCE
1. choose the brush "pencil 2b(mypaint)" or other mypaint brushes
2. use pen to slide the size of brush
3. draw by this brush,you can find the problem

SOFTWARE/OS VERSIONS
Windows: win10