Any script out there that handles "unknown" custom windows by their names may have troubles - because for many commands some "quoting" of window names with spaces is unavoidable, and these scripts lack it. Think of the analogical need of quotes in many commands to handle path-/filenames that contain spaces.
I do not run such a script on my own, yet I've seen scripts that for example do "show a sorted list for all (custom) windows (a table with infos and popups to change e.g. font sizes)"; "re-arrange and resize all visible windows (incl. custom ones) acc. to a specific pattern"; "quick hide / show all "desktoped" windows (including custom windows of course)"; "aline something to all windows that belong to a specific scon" ...
In my opinion, window names should conveniently (for practical reasons) remain limited to a non-spaced "string" of chars (like e.g. a hash table name). If you don't want to use hard spaces due to the fonts issue, a window's titlebar may always be manipulated via /titlebar, as qwerty pointed out.
