Among other things, this customization defines a macro-command called docb.openInDefaultViewer
and adds a custom binding for it. See configuration element binding.
<command name="docb.openInDefaultViewer">
<macro>
<sequence>
<get context="$implicitElement/@url" expression="resolve-uri(.)" />
<command name="start" parameter="helper(defaultViewer) '%_'" />
</sequence>
</macro>
</command>
<binding>
<keyPressed code="F2" />
<charTyped char="o" />
<command name="docb.openInDefaultViewer" />
</binding>
.
more macro-commands and bindings
.
.
A tutorial about macro-commands and the reference of all built-in commands (such as the start
command used to define the above macro) are found in another document: XMLmind XML Editor - Commands.