src/vs/workbench/contrib/preferences/browser/keybindingsEditor.ts/KeybindingsEditor/createOverlayContainer
class KeybindingsEditor:	private createOverlayContainer(parent: HTMLElement): void {
		this.overlayContainer = DOM.append(parent, $('.overlay-container'));
		this.overlayContainer.style.position = 'absolute';
		this.overlayContainer.style.zIndex = '40'; // has to greater than sash z-index which is 35
		this.defineKeybindingWidget = this._register(this.instantiationService.createInstance(DefineKeybindingWidget, this.overlayContainer));
		this._register(this.defineKeybindingWidget.onDidChange(keybindingStr => this.defineKeybindingWidget.printExisting(this.keybindingsEditorModel!.fetch(`"${keybindingStr}"`).length)));
		this._register(this.defineKeybindingWidget.onShowExistingKeybidings(keybindingStr => this.searchWidget.setValue(`"${keybindingStr}"`)));
		this.hideOverlayContainer();
	}