Use the :filter-window hook for this:
(:add-hook (in jwno/context :hook-manager) :filter-window
(fn [_hwnd uia _exe _desktop]
(not= "SomeNaughtyWindowClass" (:get_CachedClassName uia))))This code ignores windows according to their class names. Change (:get_CachedClassName uia) into (:get_CachedName uia) if you want to check the windows' title instead.
Please see Windows documentation for other useful properties you can get from the uia object.