+icon: argument is the name of the LFUN such as "paste". The syntax is the same
+ as what is used in the bind and ui files. The output is the icon use in
+ the toolbar for this LFUN. Alternatively, argument can be the icon path
+ without extension specified with respect to the images directory.
+
+buffer: argument can be one of "name", "path", "class". This inset output the