Fire model view close event when destroyed (#1427)

src/sql/parts/modelComponents/modelViewContent.component.ts

@@ -54,6 +54,11 @@ export class ModelViewContent extends ViewBase implements OnInit, IModelView {
 		}));
 	}
 
+	ngOnDestroy() {
+		this._onDestroy.fire();
+		super.ngOnDestroy();
+	}
+
 	public layout(): void {
 	}
 

src/sql/parts/modelComponents/viewBase.ts

@@ -27,6 +27,8 @@ const componentRegistry = <IComponentRegistry>Registry.as(Extensions.ComponentCo
 export abstract class ViewBase extends AngularDisposable implements IModelView {
 	protected readonly modelStore: IModelStore;
 	protected rootDescriptor: IComponentDescriptor;
+	protected _onDestroy = new Emitter<void>();
+	public readonly onDestroy = this._onDestroy.event;
 	constructor(protected changeRef: ChangeDetectorRef) {
 		super();
 		this.modelStore = new ModelStore();

src/sql/services/model/modelViewService.ts

@@ -23,4 +23,5 @@ export interface IModelView extends IView {
 	registerEvent(componentId: string);
 	onEvent: Event<any>;
 	validate(componentId: string): Thenable<boolean>;
+	readonly onDestroy: Event<void>;
 }

src/sql/workbench/api/node/mainThreadModelView.ts

@@ -36,6 +36,7 @@ export class MainThreadModelView extends Disposable implements MainThreadModelVi
 				let handle = MainThreadModelView._handlePool++;
 				this._dialogs.set(handle, view);
 				this._proxy.$registerWidget(handle, view.id, view.connection, view.serverInfo);
+				view.onDestroy(() => this._proxy.$onClosed(handle));
 			}
 		});
 	}