Dave,
Forget last post I thought V5 was no longer working as earlier I could not open it, open again now and I understand how the buttons work but my question remains. V5 seems to work just like the Threshold Tool in NX2 but as stated already in V5 lost shadows are shown when they are not shown in NX2.
The way the lost shadows work is any parts of the image that are purely black, meaning their RGB value is (0, 0, 0), will be replaced with the blue color you saw earlier. Seeing large areas of blue when using this feature will indicate that your picture is underexposed in those areas.
The way the blown highlights work is any parts of the image that are purely white, meaning their RGB value is (255, 255, 255), will be replaced with a red color. Seeing large areas of red when using this feature will indicate that your picture is overexposed in those areas.
Both of those features are there to help you determine if your image needs further post-processing work. If you turn them on and don't see large swaths of the replaced color then in regards to exposure, you're good. For instance in your picture, the blue only appears in very small amounts and mostly under the palm fronds. Looks like your shadow detail is pretty good to me.
As for the histograms in your screen shots of the two versions of Photo Mechanic, they're identical.
HTH,
-Kirk