I've spent way more time than I should've trying to add external page to lightbox. Looked at the demos, read some how-to articles, nothing worked. Check this checkbox, check that checkbox, set this and set that... and still no result. Even the docs/demos are confusing... check this sample code, but I won't tell you what checkboxes to check in order that this sample code to work.
Very confusing, very dissapointed.
Edit: ...and I don't see any support either, lots of users posted questions with responses only from community, not the author.