add event to capture state and reapply when necessary (#6246)

src/sql/base/browser/ui/panel/panel.ts

@@ -33,6 +33,8 @@ export interface IPanelView {
 	layout(dimension: DOM.Dimension): void;
 	focus(): void;
 	remove?(): void;
+	onShow?(): void;
+	onHide?(): void;
 }
 
 export interface IPanelTab {
@@ -190,6 +192,9 @@ export class TabbedPanel extends Disposable {
 				shownTab.header.setAttribute('aria-selected', 'false');
 				if (shownTab.body) {
 					shownTab.body.remove();
+					if (shownTab.tab.view.onHide) {
+						shownTab.tab.view.onHide();
+					}
 				}
 			}
 		}
@@ -215,6 +220,9 @@ export class TabbedPanel extends Disposable {
 		DOM.addClass(tab.header, 'active');
 		tab.header.setAttribute('aria-selected', 'true');
 		this._onTabChange.fire(id);
+		if (tab.tab.view.onShow) {
+			tab.tab.view.onShow();
+		}
 		if (this._currentDimensions) {
 			this._layoutCurrentTab(new DOM.Dimension(this._currentDimensions.width, this._currentDimensions.height - this.headersize));
 		}

src/sql/workbench/parts/query/browser/queryResultsView.ts

@@ -65,6 +65,8 @@ class MessagesView extends Disposable implements IPanelView {
 class ResultsView extends Disposable implements IPanelView {
 	private gridPanel: GridPanel;
 	private container = document.createElement('div');
+	private _state: GridPanelState;
+	private _runner: QueryRunner;
 
 	constructor(private instantiationService: IInstantiationService) {
 		super();
@@ -94,7 +96,20 @@ class ResultsView extends Disposable implements IPanelView {
 		this.container.remove();
 	}
 
+	onHide(): void {
+		this._state = this.gridPanel.state;
+		this.gridPanel.clear();
+	}
+
+	onShow(): void {
+		if (this._state) {
+			this.state = this._state;
+			this.queryRunner = this._runner;
+		}
+	}
+
 	public set queryRunner(runner: QueryRunner) {
+		this._runner = runner;
 		this.gridPanel.queryRunner = runner;
 	}