<p>I am writing a text editor which has an option to display a bullet in place of any invisible Unicode character.  Unfortunately there appears to be no easy way to determine whether a Unicode character is invisible.</p>

<p>I need to find a text file containing every Unicode character in order that I can look through for invisible characters.  Would anyone know where I can find such a file?</p>

<p>EDIT: I am writing this app in Cocoa for Mac OS X.</p>

Its an impossible task, Unicode supports even Klingon, so it's not going to work. However most text editors use the standard ANSI invisible characters. And if your Unicode library is good, it will support finding equivalent characters and/or categories, you can use these two features to do it as well as any editor out there
Edit:
Yes I was being silly about Klingon support, but that doesn't make it not true... of course Klingon is not supported by the Consortium, however there is a movement for Klingon in the Unicode's "Private Use Area" defined for Klingon alphabet (U+F8D0 - U+F8FF).
Link here
for those interested :)
Note:
Wonder what editor Klingon programmers use...