Bug 123040 [Commands] request: display help topic
I'm going to attach a patch to "command-ify" the opening of help topics. The command takes a parameter which is the href of a help topic. The default handler uses IWorkbenchHelpSystem.displayHelpResource(String) with the href parameter. If no parameter was given, the default handler calls IWorkbenchHelpSystem.displayHelp() instead to simply open the help system. Note that this looks like it should be opened against User Assistance, but the plugins that should be patched (I think) are org.eclipse.ui and org.eclipse.ui.workbench, so I opened against UI.
bundles/org.eclipse.core.commands/src/org/eclipse/core/commands/ParameterizedCommand.java
* Constructs a new instance of <code>ParameterizedCommand</code> with
	 * specific values for zero or more of its parameters.
	 * 
	 * @param command
	 *            The command that is parameterized; must not be
	 *            <code>null</code>.
	 * @param parameterizations
	 *            An array of parameterizations binding parameters to values for
	 *            the command. This value may be <code>null</code>. This
	 *            argument is not copied; if you need to make changes to it
	 *            after constructing this parameterized command, then make a
	 *            copy yourself.
	 */
	public ParameterizedCommand(final Command command,
			final Parameterization[] parameterizations) {
		if (command == null) {
			throw new NullPointerException(
					"A parameterized command cannot have a null command"); 
		}
		this.command = command;
		this.parameterizations = (parameterizations == null || parameterizations.length == 0) ? null
				: parameterizations;
	}
	/*
	 * (non-Javadoc)
	 * 
	 * @see java.lang.Comparable#compareTo(java.lang.Object)
	 */
	public final int compareTo(final Object object) {
		final ParameterizedCommand command = (ParameterizedCommand) object;