output: introduce onActiveOutputChannel

fixes #3892

src/vs/base/browser/ui/actionbar/actionbar.ts

@@ -724,7 +724,7 @@ export class SelectActionItem extends BaseActionItem {
 	private select: HTMLSelectElement;
 	private options: string[];
 	private selected: number;
-	private toDispose: lifecycle.IDisposable[];
+	protected toDispose: lifecycle.IDisposable[];
 
 	constructor(ctx: any, action: IAction, options: string[], selected: number) {
 		super(ctx, action);

src/vs/workbench/parts/output/browser/outputActions.ts

@@ -8,7 +8,6 @@ import {TPromise} from 'vs/base/common/winjs.base';
 import nls = require('vs/nls');
 import {Registry} from 'vs/platform/platform';
 import arrays = require('vs/base/common/arrays');
-import {IDisposable} from 'vs/base/common/lifecycle';
 import {IAction, Action} from 'vs/base/common/actions';
 import {EditorAction} from 'vs/editor/common/editorAction';
 import {Behaviour} from 'vs/editor/common/editorActionEnablement';
@@ -108,15 +107,14 @@ export class SwitchOutputAction extends Action {
 
 export class SwitchOutputActionItem extends SelectActionItem {
 	private input: OutputEditorInput;
-	private outputListenerDispose: IDisposable;
 
 	constructor(
 		action: IAction,
 		@IOutputService private outputService: IOutputService
 	) {
 		super(null, action, SwitchOutputActionItem.getChannels(outputService), Math.max(0, SwitchOutputActionItem.getChannels(outputService).indexOf(outputService.getActiveChannel())));
-
-		this.outputListenerDispose = this.outputService.onOutputChannel(this.onOutputChannel, this);
+		this.toDispose.push(this.outputService.onOutputChannel(this.onOutputChannel, this));
+		this.toDispose.push(this.outputService.onActiveOutputChannel(this.onOutputChannel, this));
 	}
 
 	private onOutputChannel(): void {
@@ -135,12 +133,6 @@ export class SwitchOutputActionItem extends SelectActionItem {
 
 	public dispose(): void {
 		super.dispose();
-
-		if (this.outputListenerDispose) {
-			this.outputListenerDispose.dispose();
-			delete this.outputListenerDispose;
-		}
-
 		delete this.input;
 	}
 }

src/vs/workbench/parts/output/common/output.ts

@@ -99,6 +99,11 @@ export interface IOutputService {
 	 * Allows to register on a new Output channel getting filled with output
 	 */
 	onOutputChannel: Event<string>;
+
+	/**
+	 * Allows to register on active output channel change
+	 */
+	onActiveOutputChannel: Event<string>;
 }
 
 export interface IOutputChannelRegistry {

src/vs/workbench/parts/output/common/outputServices.ts

@@ -30,6 +30,7 @@ export class OutputService implements IOutputService {
 
 	private _onOutput: Emitter<IOutputEvent>;
 	private _onOutputChannel: Emitter<string>;
+	private _onActiveOutputChannel: Emitter<string>;
 
 	constructor(
 		@IStorageService private storageService: IStorageService,
@@ -40,6 +41,7 @@ export class OutputService implements IOutputService {
 	) {
 		this._onOutput = new Emitter<IOutputEvent>();
 		this._onOutputChannel = new Emitter<string>();
+		this._onActiveOutputChannel = new Emitter<string>();
 
 		this.receivedOutput = Object.create(null);
 
@@ -55,6 +57,10 @@ export class OutputService implements IOutputService {
 		return this._onOutputChannel.event;
 	}
 
+	public get onActiveOutputChannel(): Event<string> {
+		return this._onActiveOutputChannel.event;
+	}
+
 	public append(channel: string, output: string): void {
 
 		// Initialize
@@ -114,6 +120,7 @@ export class OutputService implements IOutputService {
 	public showOutput(channel: string, preserveFocus?: boolean): TPromise<IEditor> {
 		this.activeChannel = channel;
 		this.storageService.store(OUTPUT_ACTIVE_CHANNEL_KEY, this.activeChannel, StorageScope.WORKSPACE);
+		this._onActiveOutputChannel.fire(channel); // emit event that we a new channel is active
 
 		return this.panelService.openPanel(OUTPUT_PANEL_ID, !preserveFocus).then((outputPanel: OutputPanel) => {
 			return outputPanel && outputPanel.setInput(OutputEditorInput.getInstance(this.instantiationService, channel), EditorOptions.create({ preserveFocus: preserveFocus })).