It can use either a Trolltech Qt widget
or KDE's own KHTML widget
to show the text (change widget from the Settings menu). When there is CHM file that wouldn't display correctly, and changing widgets may solve the problem.
Help Explorer Viewer
developed by Kama Software
, is free but not open source. It comes in both Windows and Linux versions, which is an advantage if you work with dual booting systems or in an environment with both operating systems. You can use Help Explorer Viewer to view not only CHM files, but HLP (older) and HXS (newer) help file formats as well. According to the Web site, you can integrate Help Explorer Viewer into your application through its API.
is an open source Gtk2+ package for GNOME whose Web site is written mostly in Chinese
CHM Reader add-on for Firefox
Firefox users can download the CHM Reader
add-on, currently at version 0.2.1.1. Installation is simple. The utility adds a new Open CHM Files entry to the Firefox File menu. When you open a CHM file, the table of contents is hidden by default, but you can bring it up by pressing Ctrl-E. Viewing files works fine, but CHM Reader doesn't offer a global search function, and the Firefox search function works only within the current page.
, and KCHM