I found out that there is a way to show clipping areas in Photoshop when adjusting levels via an adjustment layer. While moving the slider, you hold down the ALT key.
I tried this in PSP X3 and it does not work. Does anyone know if this feature for seeing the clipping preview is available in Paint Shop Pro? It's a nice feature.
Not sure if it's in X3, but in X4 you can press and hold CTRL while adjusting the white and black point to reveal clipping. In X4 this does not seem to working in the Levels Adjustment Layer.