If the variable HelpDefaultTopic is set (with the !set command or otherwise) to an empty string, pressing the Help button will not bring up the default top-level window. However, clicking on objects and buttons will bring up help topics as usual. One can also set this variable to a URL or database keyword, the content from which will appear in the initial window as the default topic.
Clicking on a colored HTML reference will bring up the text of the selected topic. If button 1 is used to click, the text will appear in the same window. If button 2 is used to click, a new help window containing the selected topic will appear.
The help system operates in one of two modes. The default mode is to use a single window for each new topic generated by pressing a command or menu button. In the multi-window implementation, which can be selected in Xic by selecting the Multi-Window Mode button in the Help Menu, or by setting the boolean variable HelpMultiWin with the !set command, a separate window is brought up for each press of a command button or menu item while in help mode. In either case, clicking on a link may or may not produce a new window, depending upon whether button 1 or button 2 was clicked.
Text shown in the viewer that is not part of an image can be selected by dragging with button 1, and can be pasted into other windows in the usual way.
The viewer can be used to display any text file or URL. In Xic and its derivatives, pressing the question mark key (``?'') will prompt the user for text to display. The !help command has the same effect. In WRspice, the text to display can follow the ``help'' command keyword on the command line. The name given to the command, or to to the Open command in the viewer's File menu, can be
If the given name can be resolved, the resulting page will be displayed in the viewer. Also, the HTML viewer is sensitive as a drop receiver. If a file name or URL is dragged into the viewer and dropped, that file or URL is read into the viewer, after confirmation.
The ability to access general URLs should be convenient for accessing information from the internet while using Xic. The prefix ``http://'' must be provided with the URL. Thus, for example,
? http://wrcad.comwill bring up the Whiteley Research web page in Xic or WRspice. The links can be followed by clicking in the usual way. Of course, the computer must have internet access for web pages to be accessible.
The given URL is not relative to the current page, however if a `+' is given before the URL, it will be treated as relative. For example, if the viewer is currently displaying http://www.foo.bar, if one enters ``/dir/file.html'', the display will be updated to /dir/file.html on the local machine. If instead one enters ``+/dir/file.html'', the display will be loaded with http://www.foo.bar/dir/file.html.
The HTTP capability imposes some obvious limitations on the string tokens which can be used in the help database. These keywords should not use the `/' character, or begin with a protocol specifier such as ``http:''.
HTML files on a local machine can be loaded by giving the full path name to the file. Relative references will be found. HTML files will also be found if they are located in the help path, however relative references will be found only if the referenced file is also in the help path. If a directory is referenced rather than a file, a formatted list of the files in the directory is shown.
If a filename passed to the viewer has one of the following extensions, the text is shown verbatim. The (case insensitive) extensions for plain-text files are ``.txt'', ``.log'', ``.scr'', ``.sh'', ``.csh'', ``.c'', ``.cc'', ``.cpp'', ``.h'', ``.py'', ``.tcl'', and ``.tk''
Holding Shift while clicking on an anchor that points to a URL which specifies a file on a remote system will download the file. References to files with extensions ``.rpm'', ``.gz'', and other common binary file suffixes will automatically cause downloading rather than viewing. When downloading, the file selection pop-up will appear, pre-loaded with the file name (or ``http_return'' if the name is not known) in the current directory. One can change the saved name and the directory of the file to be downloaded. Pressing the Download button will start downloading. A pop-up will appear that monitors the transfer, which can be aborted with the Cancel button.