Curious if this was looked into at all and if I should look for more evidence. Seems like a simple code fix. I'm not versed in the C++ code of P1999 but I guess it would look something like this:
Client:
[You must be logged in to view images. Log in or Register.]nTradeNPC()
{
this.clearInvis();
//do other stuff
}
I don't know your specific implementation here on P1999 but I assume the invis/hide "bug/feature" existed in classic EQ because the method that cleared invis only cleared the top most layer of invis and assumed that would be enough to make the client appear. Even if you don't choose to re-implement this classic feature, I'm still curious what your method call looks like so I get a better feel for how this game is coded.