Z-BRUSH: Partial Visibility + Clip Brushes

Select Selection or Clip Brush - hold Shift+Ctrl while selecting brush from popup

Show mesh portion – Shift+Ctrl+Click, release keys & drag (green selection area)

Hide mesh portion - Shift+Ctrl+Click, release keys & drag - press Alt (red selection area)

Move selection or clip area - 'press Spacebar without releasing mouse/pen

Show entire mesh - Shift+Ctrl+Click Background

Show only selected Polygroup (on fully visible mesh) - Shift+Ctrl+Click

Hide selected Polygroup (on fully visible mesh) - Shift+Ctrl+Click twice

Hide selected Polygroup (on partially visible mesh) - Shift+Ctrl+Click

Reverse visibility - Shift+Ctrl+Click & drag Background

Hide edge loop - with Lasso option selected, Shift+Ctrl+click on edge that crosses loop

ClipCurve add soft direction change - click Alt once

ClipCurve add sharp direction change - click Alt twice

reverse clip area - Alt (hold down)