I did not use the show/hide function in DW3, but I have worked with DW4. The only problem I had with mutiple layers was the layer names need to be unique for the first few letters of the layer name or it gets confused. The function does not check the whole string. Another words mylayer1 and mylayer2 are treated as the same where as 1mylayer and 2mylayer did work. This was only a problem when I had lots of named layers. I don't know if this helps but it caused me problems.