Bug 187796 [KeyBindings] IBindingService cannot return best active bindings for a ParameterizedCommand
IBindingService only supports getBestActiveBindingFor(final String commandId) ... there must be an equivalent method for ParameterizedCommands PW
bundles/org.eclipse.jface/src/org/eclipse/jface/bindings/BindingManager.java
* active bindings and return.
		 */
		CachedBindingSet existingCache = (CachedBindingSet) cachedBindings
				.get(bindingCache);
		if (existingCache == null) {
			existingCache = bindingCache;
			cachedBindings.put(existingCache, existingCache);
		}
		Map commandIdsByTrigger = existingCache.getBindingsByTrigger();
		if (commandIdsByTrigger != null) {
			if (DEBUG) {
				Tracing.printTrace("BINDINGS", "Cache hit"); 
			}
			setActiveBindings(commandIdsByTrigger, existingCache
					.getTriggersByCommandId(), existingCache.getPrefixTable(),
					existingCache.getConflictsByTrigger());
			return;
		}
		
		if (DEBUG) {
			Tracing.printTrace("BINDINGS", "Cache miss"); 
		}
		
		commandIdsByTrigger = new HashMap();
		final Map triggersByParameterizedCommand = new HashMap();
		final Map conflictsByTrigger = new HashMap();
		computeBindings(activeContextTree, commandIdsByTrigger,
				triggersByParameterizedCommand, conflictsByTrigger);
		existingCache.setBindingsByTrigger(commandIdsByTrigger);
		existingCache.setTriggersByCommandId(triggersByParameterizedCommand);