While I've been learning zBrush I've come across a few things that have driven me crazy.

Here's a video tutorial in two parts that show some of the problems and my solutions/ / workarounds. There are probably other / better solutions but this is what worked for me.

Part 1:
http://youtu.be/A_s9GDiEQmw

Part 2:
http://youtu.be/zxcdlle-LbA

Hope it helps...

Cheers
Chris