src/vs/workbench/browser/parts/panel/panelPart.ts/PanelPart/setPlaceholderViewContainers
class PanelPart:	private setPlaceholderViewContainers(placeholderViewContainers: IPlaceholderViewContainer[]): void {
		this.placeholderViewContainersValue = JSON.stringify(placeholderViewContainers);
	}