On my system, after opening the attached HTML document in Geany and changing its file type from "HTML" to "None", a strange colorful underline appears. The underline disappears after doing Ctrl-A Ctrl-X Ctrl-V.
Originally reported to geany mailing list: http://lists.uvena.de/geany/2012-February/007779.html
Geany version (compiled from Git):
geany 1.22 (git >= ca340a8) (built on Feb 12 2012 with GTK 2.24.10, GLib 2.30.2)