Finder 6.x allows a maximum of 13 windows open at once. You can use
ResEdit to change this value. Here are the steps:
1) Work only on a COPY of your Finder.
2) Start ResEdit.
3) Open the Finder file from ResEdit.
4) Open the LAYO resource named ID=128. (It's probably the only one of
that type.)
5) Scroll until you find the layout default called "Max # of windows".
It's at the bottom of the list.
6) Change this to the desired value.
7) Quit ResEdit and answer Yes to "Save 'Finder' before closing?"
Changing this value to a higher number causes the Finder to use more memory.
You may have to allocate more memory for the Finder, if you are running
MultiFinder.