ratpoison can intentionally not manage windows. ratpoison keeps a list of strings and if any new window's name matches a string in the list, then it will not be picked up and managed by ratpoison.
The following are commands to manipulate this list
Add text to the unmanaged window list. Any window whose name matches any of the strings in the unmanaged window list will not be handled in any way by ratpoison. This only applies to new windows (not windows already managed by ratpoison).
When called with no arguments, the list is returned.