src/vs/workbench/api/common/extHostStatusBar.ts/ExtHostStatusBarEntry/backgroundColor
class ExtHostStatusBarEntry:	public set backgroundColor(color: ThemeColor | undefined) {
		if (color && !ExtHostStatusBarEntry.ALLOWED_BACKGROUND_COLORS.has(color.id)) {
			color = undefined;
		}

		this._backgroundColor = color;
		this.update();
	}