diff --git a/packages/trace-viewer/src/ui/filmStrip.css b/packages/trace-viewer/src/ui/filmStrip.css
index 9570de199e..d9639b12bc 100644
--- a/packages/trace-viewer/src/ui/filmStrip.css
+++ b/packages/trace-viewer/src/ui/filmStrip.css
@@ -19,6 +19,7 @@
   display: flex;
   flex-direction: column;
   position: relative;
+  min-height: 50px;
 }
 
 .film-strip-lane {
diff --git a/packages/trace-viewer/src/ui/sourceTab.tsx b/packages/trace-viewer/src/ui/sourceTab.tsx
index 248dd2ebef..6ed5431c28 100644
--- a/packages/trace-viewer/src/ui/sourceTab.tsx
+++ b/packages/trace-viewer/src/ui/sourceTab.tsx
@@ -30,7 +30,8 @@ type StackInfo = {
 
 export const SourceTab: React.FunctionComponent<{
   action: ActionTraceEvent | undefined,
-}> = ({ action }) => {
+  hideStackFrames?: boolean,
+}> = ({ action, hideStackFrames }) => {
   const [lastAction, setLastAction] = React.useState<ActionTraceEvent | undefined>();
   const [selectedFrame, setSelectedFrame] = React.useState<number>(0);
 
@@ -69,7 +70,7 @@ export const SourceTab: React.FunctionComponent<{
 
   const targetLine = stackInfo.frames[selectedFrame]?.line || 0;
   const error = action?.error?.message;
-  return <SplitView sidebarSize={200} orientation='horizontal'>
+  return <SplitView sidebarSize={200} orientation='horizontal' sidebarHidden={hideStackFrames}>
     <CodeMirrorWrapper text={content} language='javascript' highlight={[{ line: targetLine, type: error ? 'error' : 'running', message: error }]} revealLine={targetLine} readOnly={true} lineNumbers={true}></CodeMirrorWrapper>
     <StackTraceView action={action} selectedFrame={selectedFrame} setSelectedFrame={setSelectedFrame}></StackTraceView>
   </SplitView>;
diff --git a/packages/trace-viewer/src/ui/timeline.tsx b/packages/trace-viewer/src/ui/timeline.tsx
index 48901bb396..4c6eb2f099 100644
--- a/packages/trace-viewer/src/ui/timeline.tsx
+++ b/packages/trace-viewer/src/ui/timeline.tsx
@@ -41,7 +41,8 @@ export const Timeline: React.FunctionComponent<{
   model: MultiTraceModel | undefined,
   selectedAction: ActionTraceEvent | undefined,
   onSelected: (action: ActionTraceEvent) => void,
-}> = ({ model, selectedAction, onSelected }) => {
+  hideTimelineBars?: boolean,
+}> = ({ model, selectedAction, onSelected, hideTimelineBars }) => {
   const [measure, ref] = useMeasure<HTMLDivElement>();
   const barsRef = React.useRef<HTMLDivElement | null>(null);
 
@@ -50,6 +51,10 @@ export const Timeline: React.FunctionComponent<{
 
   const { boundaries, offsets } = React.useMemo(() => {
     const boundaries = { minimum: model?.startTime || 0, maximum: model?.endTime || 30000 };
+    if (boundaries.minimum > boundaries.maximum) {
+      boundaries.minimum = 0;
+      boundaries.maximum = 30000;
+    }
     // Leave some nice free space on the right hand side.
     boundaries.maximum += (boundaries.maximum - boundaries.minimum) / 20;
     return { boundaries, offsets: calculateDividerOffsets(measure.width, boundaries) };
@@ -95,41 +100,34 @@ export const Timeline: React.FunctionComponent<{
   let targetBar: TimelineBar | undefined = bars.find(bar => bar.action === selectedAction);
   targetBar = hoveredBar || targetBar;
 
-  const findHoveredBarIndex = (x: number, y: number) => {
+  const findHoveredBarIndex = (x: number) => {
     const time = positionToTime(measure.width, boundaries, x);
     const time1 = positionToTime(measure.width, boundaries, x - 5);
     const time2 = positionToTime(measure.width, boundaries, x + 5);
     let index: number | undefined;
-    let yDistance: number | undefined;
     let xDistance: number | undefined;
     for (let i = 0; i < bars.length; i++) {
       const bar = bars[i];
-      const yMiddle = kBarHeight / 2 + barTop(bar);
       const left = Math.max(bar.leftTime, time1);
       const right = Math.min(bar.rightTime, time2);
       const xMiddle = (bar.leftTime + bar.rightTime) / 2;
       const xd = Math.abs(time - xMiddle);
-      const yd = Math.abs(y - yMiddle);
       if (left > right)
         continue;
       // Prefer closest yDistance (the same bar), among those prefer the closest xDistance.
-      if (index === undefined ||
-          (yd < yDistance!) ||
-          (Math.abs(yd - yDistance!) < 1e-2 && xd < xDistance!)) {
+      if (index === undefined || xd < xDistance!) {
         index = i;
         xDistance = xd;
-        yDistance = yd;
       }
     }
     return index;
   };
 
   const onMouseMove = (event: React.MouseEvent) => {
-    if (!ref.current || !barsRef.current)
+    if (!ref.current)
       return;
     const x = event.clientX - ref.current.getBoundingClientRect().left;
-    const y = event.clientY - barsRef.current.getBoundingClientRect().top;
-    const index = findHoveredBarIndex(x, y);
+    const index = findHoveredBarIndex(x);
     setPreviewPoint({ x, clientY: event.clientY });
     setHoveredBarIndex(index);
   };
@@ -141,11 +139,10 @@ export const Timeline: React.FunctionComponent<{
 
   const onClick = (event: React.MouseEvent) => {
     setPreviewPoint(undefined);
-    if (!ref.current || !barsRef.current)
+    if (!ref.current)
       return;
     const x = event.clientX - ref.current.getBoundingClientRect().left;
-    const y = event.clientY - barsRef.current.getBoundingClientRect().top;
-    const index = findHoveredBarIndex(x, y);
+    const index = findHoveredBarIndex(x);
     if (index === undefined)
       return;
     const entry = bars[index].action;
@@ -162,7 +159,7 @@ export const Timeline: React.FunctionComponent<{
           </div>;
         })
       }</div>
-      <div className='timeline-lane timeline-labels'>{
+      {!hideTimelineBars && <div className='timeline-lane timeline-labels'>{
         bars.map((bar, index) => {
           return <div key={index}
             className={'timeline-label ' + bar.className + (targetBar === bar ? ' selected' : '')}
@@ -174,8 +171,8 @@ export const Timeline: React.FunctionComponent<{
             {bar.label}
           </div>;
         })
-      }</div>
-      <div className='timeline-lane timeline-bars' ref={barsRef}>{
+      }</div>}
+      {!hideTimelineBars && <div className='timeline-lane timeline-bars' ref={barsRef}>{
         bars.map((bar, index) => {
           return <div key={index}
             className={'timeline-bar ' + (bar.action ? 'action ' : '') + (bar.event ? 'event ' : '') + bar.className + (targetBar === bar ? ' selected' : '')}
@@ -187,7 +184,7 @@ export const Timeline: React.FunctionComponent<{
             title={bar.title}
           ></div>;
         })
-      }</div>
+      }</div>}
       <FilmStrip model={model} boundaries={boundaries} previewPoint={previewPoint} />
       <div className='timeline-marker timeline-marker-hover' style={{
         display: (previewPoint !== undefined) ? 'block' : 'none',
@@ -239,7 +236,6 @@ function trimRight(s: string, maxLength: number): string {
   return s.length <= maxLength ? s : s.substring(0, maxLength - 1) + '\u2026';
 }
 
-const kBarHeight = 11;
 function barTop(bar: TimelineBar): number {
   return bar.event ? 22 : (bar.action?.method === 'waitForEventInfo' ? 0 : 11);
 }
diff --git a/packages/trace-viewer/src/ui/watchMode.tsx b/packages/trace-viewer/src/ui/watchMode.tsx
index 3079411dd5..e08fc8e433 100644
--- a/packages/trace-viewer/src/ui/watchMode.tsx
+++ b/packages/trace-viewer/src/ui/watchMode.tsx
@@ -346,7 +346,7 @@ export const TraceView: React.FC<{
   const xterm = <XtermWrapper source={xtermDataSource}></XtermWrapper>;
   return <Workbench model={model} output={xterm} rightToolbar={[
     <ToolbarButton icon='trash' title='Clear output' onClick={() => xtermDataSource.clear()}></ToolbarButton>,
-  ]}/>;
+  ]} hideTimelineBars={true} hideStackFrames={true} />;
 };
 
 declare global {
diff --git a/packages/trace-viewer/src/ui/workbench.tsx b/packages/trace-viewer/src/ui/workbench.tsx
index 6be206122d..2f50123aa9 100644
--- a/packages/trace-viewer/src/ui/workbench.tsx
+++ b/packages/trace-viewer/src/ui/workbench.tsx
@@ -35,7 +35,9 @@ export const Workbench: React.FunctionComponent<{
   model?: MultiTraceModel,
   output?: React.ReactElement,
   rightToolbar?: React.ReactElement[],
-}> = ({ model, output, rightToolbar }) => {
+  hideTimelineBars?: boolean,
+  hideStackFrames?: boolean,
+}> = ({ model, output, rightToolbar, hideTimelineBars, hideStackFrames }) => {
   const [selectedAction, setSelectedAction] = React.useState<ActionTraceEvent | undefined>(undefined);
   const [highlightedAction, setHighlightedAction] = React.useState<ActionTraceEvent | undefined>();
   const [selectedNavigatorTab, setSelectedNavigatorTab] = React.useState<string>('actions');
@@ -49,7 +51,7 @@ export const Workbench: React.FunctionComponent<{
     if (failedAction)
       setSelectedAction(failedAction);
     // In the UI mode, selecting the first error should reveal source.
-    if (output)
+    if (failedAction && output)
       setSelectedPropertiesTab('source');
   }, [model, output, selectedAction, setSelectedAction, setSelectedPropertiesTab]);
 
@@ -60,7 +62,7 @@ export const Workbench: React.FunctionComponent<{
 
   const tabs: TabbedPaneTabModel[] = [
     { id: 'call', title: 'Call', render: () => <CallTab action={activeAction} sdkLanguage={sdkLanguage} /> },
-    { id: 'source', title: 'Source', count: 0, render: () => <SourceTab action={activeAction} /> },
+    { id: 'source', title: 'Source', count: 0, render: () => <SourceTab action={activeAction} hideStackFrames={hideStackFrames}/> },
     { id: 'console', title: 'Console', count: consoleCount, render: () => <ConsoleTab action={activeAction} /> },
     { id: 'network', title: 'Network', count: networkCount, render: () => <NetworkTab action={activeAction} /> },
   ];
@@ -73,6 +75,7 @@ export const Workbench: React.FunctionComponent<{
       model={model}
       selectedAction={activeAction}
       onSelected={action => setSelectedAction(action)}
+      hideTimelineBars={hideTimelineBars}
     />
     <SplitView sidebarSize={output ? 250 : 350} orientation={output ? 'vertical' : 'horizontal'}>
       <SplitView sidebarSize={250} orientation='horizontal' sidebarIsFirst={true}>