src/vs/workbench/contrib/markers/browser/markersTreeViewer.ts/MarkerWidget/renderMultilineActionbar
class MarkerWidget:	private renderMultilineActionbar(marker: Marker): void {
		const viewModel = this.markersViewModel.getViewModel(marker);
		const multiline = viewModel && viewModel.multiline;
		const action = new Action(toggleMultilineAction);
		action.enabled = !!viewModel && marker.lines.length > 1;
		action.tooltip = multiline ? localize('single line', "Show message in single line") : localize('multi line', "Show message in multiple lines");
		action.class = ThemeIcon.asClassName(multiline ? expandedIcon : collapsedIcon);
		action.run = () => { if (viewModel) { viewModel.multiline = !viewModel.multiline; } return Promise.resolve(); };
		this.multilineActionbar.push([action], { icon: true, label: false });
	}