make editor area return more intuitive

src/vs/workbench/browser/parts/editor/editorPart.ts

@@ -110,6 +110,9 @@ export class EditorPart extends Part implements EditorGroupsServiceImpl, IEditor
 	private _onDidPreferredSizeChange: Emitter<void> = this._register(new Emitter<void>());
 	get onDidPreferredSizeChange(): Event<void> { return this._onDidPreferredSizeChange.event; }
 
+	private _onDidActivateGroup: Emitter<IEditorGroupView> = this._register(new Emitter<IEditorGroupView>());
+	get onDidActivateGroup(): Event<IEditorGroupView> { return this._onDidActivateGroup.event; }
+
 	//#endregion
 
 	private dimension: Dimension;
@@ -319,6 +322,7 @@ export class EditorPart extends Part implements EditorGroupsServiceImpl, IEditor
 		const groupView = this.assertGroupView(group);
 		this.doSetGroupActive(groupView);
 
+		this._onDidActivateGroup.fire(groupView);
 		return groupView;
 	}
 

src/vs/workbench/electron-browser/workbench.ts

@@ -502,6 +502,9 @@ export class Workbench extends Disposable implements IPartService {
 		// Listen to visible editor changes
 		this._register(this.editorService.onDidVisibleEditorsChange(() => this.onDidVisibleEditorsChange()));
 
+		// Listen to editor group activations when editor is hidden
+		this._register(this.editorPart.onDidActivateGroup(() => { if (this.editorHidden) { this.setEditorHidden(false); } }));
+
 		// Listen to editor closing (if we run with --wait)
 		const filesToWait = this.workbenchParams.configuration.filesToWait;
 		if (filesToWait) {
@@ -1272,6 +1275,8 @@ export class Workbench extends Disposable implements IPartService {
 				return !this.statusBarHidden;
 			case Parts.ACTIVITYBAR_PART:
 				return !this.activityBarHidden;
+			case Parts.EDITOR_PART:
+				return this.workbenchGrid instanceof Grid ? !this.editorHidden : true;
 		}
 
 		return true; // any other part cannot be hidden