VM uses the following layout for the mouse buttons in the folder and summary buffers.
Activate. If you click on a summary entry, that message will be
selected and become the current message. If you click on a
highlighted URL in the body of a message, that URL will be sent
to the browser specified by vm-url-browser.
Context Menu. If the mouse pointer is over the contents of the From header, button-3 pops up a menu of actions that can be taken using the author of the message as a parameter. For instance, you may want to create a virtual folder containing all the messages in the current folder written by this author. If the mouse pointer is over the contents of the Subject header, a menu of actions to be performed on the current message’s subject is produced. If button-3 is clicked over a highlighted URL, a menu of Web browsers is produced. Otherwise the normal VM mode specific menu is produced.
These button assignments work only in plain text messages. For HTML
messages, you might use an internal web browser such as w3m to display
the content, which will have its own button assignments. For instance,
w3m binds button-2 to the browser function specified by the variable
w3m-goto-article-function. You will need to set that variable to
the desired browser function to get button-2 to work in HTML messages.
In mail composition buffers only mouse button-3 is affected. Context sensitive menus are produced when that button is clicked.
VM provides a number of browser functions that you can set as the value
of vm-url-browser. An example is the function
vm-mouse-send-url-to-netscape, which sends the URL at mouse to the
Netscape browser. Other browsers supported in this way include
mosaic, mmosaic, opera, mozilla,
firefox, and konqueror, all of which have functions of the
form vm-mouse-send-url-to-xxx and vm-mouse-send-url-to-xxx-new-window. You can also set
vm-url-browser to the Emacs function browse-url, and use
the facilities defined in the ‘browse-url’ library to send URL’s to
external browsers.