Victor Wagner is working on  a "help viewer for Tk on Unix,The aim of this project is to provide same on-line documentation for cross-platform Tcl/Tk application on every platform and use native help viewer, provided by operationg system if possible.So, we modelled our platform-independent help viewer after native Windows help viewer.You can interface windows help viewer from Tcl script using Cristian Werner's winhelp extension.Native windows help system uses .chm files which are essentially archive of HTML pages, with additional information such as table of contents and keyword index.unixhelp extension allows to view help file, build from same source, as Windows .chm file, but not .chm file itself.We choose this approach, because there doesn't exist free (as free speech) tool to create .chm file. So, if you modify an application on Unix, you cannot modify help file to reflect your changes.unixhelp help file is just a zip archive which contains html pages and index files, so it is easy to modify it even if you don't have windows development tools at all.It is possible to create Tcl viewer for chm-files. There exists a library chmlib which allows to dearchive chm. So, it is possible to write tcl vfs which works on chm files.unixhelp extension uses tkhtml extension to display help pages and tclvfs extension to extract files from the archive. In order to get vfs::zip with vfs::zip you also need memchan and trf.unixhelp includes script tkhhc which automatically creates help files from Microsoft Html Help Workshop projects.