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
public static final int INDEX_PARAMETER_ID = 0;
	/**
	 * The index of the human-readable name of the parameter itself, in the
	 * parameter values.
	 * 
	 * @deprecated no longer used
	 */
	public static final int INDEX_PARAMETER_NAME = 1;
	/**
	 * The index of the human-readable name of the value of the parameter for
	 * this command.
	 * 
	 * @deprecated no longer used
	 */
	public static final int INDEX_PARAMETER_VALUE_NAME = 2;
	/**
	 * The index of the value of the parameter that the command can understand.
	 * 
	 * @deprecated no longer used
	 */
	public static final int INDEX_PARAMETER_VALUE_VALUE = 3;
	/**
	 * Escapes special characters in the command id, parameter ids and parameter
	 * values for {@link #serialize()}. The special characters
	 * {@link CommandManager#PARAMETER_START_CHAR},
	 * {@link CommandManager#PARAMETER_END_CHAR},
	 * {@link CommandManager#ID_VALUE_CHAR},
	 * {@link CommandManager#PARAMETER_SEPARATOR_CHAR} and
	 * {@link CommandManager#ESCAPE_CHAR} are escaped by prepending a
	 * {@link CommandManager#ESCAPE_CHAR} character.