diff --git a/examples/todomvc/tests/integration.spec.ts b/examples/todomvc/tests/integration.spec.ts
index ec3d4af040..007896bb2c 100644
--- a/examples/todomvc/tests/integration.spec.ts
+++ b/examples/todomvc/tests/integration.spec.ts
@@ -35,7 +35,7 @@ test.describe('New Todo', () => {
     // Make sure the list now has two todo items.
     await expect(page.getByTestId('todo-title')).toHaveText([
       TODO_ITEMS[0],
-      TODO_ITEMS[1]
+      TODO_ITEMS[1],
     ]);
 
     await checkNumberOfTodosInLocalStorage(page, 2);
diff --git a/packages/trace-viewer/src/ui/networkTab.css b/packages/trace-viewer/src/ui/networkTab.css
index b714b44769..00b252e89e 100644
--- a/packages/trace-viewer/src/ui/networkTab.css
+++ b/packages/trace-viewer/src/ui/networkTab.css
@@ -88,6 +88,7 @@
   align-items: center;
   white-space: nowrap;
   height: 100%;
+  overflow: hidden;
 }
 
 .network-request-header.filter-start.positive .network-request-start .codicon-triangle-down {
diff --git a/packages/trace-viewer/src/ui/timeline.css b/packages/trace-viewer/src/ui/timeline.css
index 411e6188c3..22865f0e48 100644
--- a/packages/trace-viewer/src/ui/timeline.css
+++ b/packages/trace-viewer/src/ui/timeline.css
@@ -82,6 +82,11 @@
 }
 
 .timeline-bar.action {
+  --action-color: var(--vscode-charts-orange);
+  --action-background-color: #d1861633;
+}
+
+.timeline-bar.action.error {
   --action-color: var(--vscode-charts-red);
   --action-background-color: #e5140033;
 }
@@ -91,6 +96,11 @@
   --action-background-color: #1a85ff33;
 }
 
+body.dark-mode .timeline-bar.action.error {
+  --action-color: var(--vscode-errorForeground);
+  --action-background-color: #f4877133;
+}
+
 .timeline-label {
   position: absolute;
   top: 0;
@@ -144,17 +154,13 @@ body.dark-mode .timeline-window-curtain {
   background-color: #161718bf;
 }
 
-.timeline-window-curtain.left {
-  border-right: 1px solid var(--vscode-panel-border);
-}
-
-.timeline-window-curtain.right {
-  border-left: 1px solid var(--vscode-panel-border);
-}
-
 .timeline-window-resizer {
   flex: none;
-  width: 6px;
+  width: 10px;
   cursor: ew-resize;
   pointer-events: all;
+  position: relative;
+  background-color: var(--vscode-panel-border);
+  border-left: 1px solid var(--vscode-panel-border);
+  border-right: 1px solid var(--vscode-panel-border);
 }
diff --git a/packages/trace-viewer/src/ui/timeline.tsx b/packages/trace-viewer/src/ui/timeline.tsx
index aeea2264af..ef6fba675a 100644
--- a/packages/trace-viewer/src/ui/timeline.tsx
+++ b/packages/trace-viewer/src/ui/timeline.tsx
@@ -33,6 +33,7 @@ type TimelineBar = {
   leftTime: number;
   rightTime: number;
   active: boolean;
+  error: boolean;
 };
 
 export const Timeline: React.FunctionComponent<{
@@ -74,6 +75,7 @@ export const Timeline: React.FunctionComponent<{
         leftPosition: timeToPosition(measure.width, boundaries, entry.startTime),
         rightPosition: timeToPosition(measure.width, boundaries, entry.endTime || boundaries.maximum),
         active: false,
+        error: !!entry.error,
       });
     }
 
@@ -87,6 +89,7 @@ export const Timeline: React.FunctionComponent<{
         leftPosition: timeToPosition(measure.width, boundaries, startTime),
         rightPosition: timeToPosition(measure.width, boundaries, endTime),
         active: false,
+        error: false,
       });
     }
     return bars;
@@ -230,7 +233,10 @@ export const Timeline: React.FunctionComponent<{
       <div className='timeline-bars'>{
         bars.map((bar, index) => {
           return <div key={index}
-            className={'timeline-bar' + (bar.action ? ' action' : '') + (bar.resource ? ' network' : '') + (bar.active ? ' active' : '')}
+            className={'timeline-bar' + (bar.action ? ' action' : '')
+                                      + (bar.resource ? ' network' : '')
+                                      + (bar.active ? ' active' : '')
+                                      + (bar.error ? ' error' : '')}
             style={{
               left: bar.leftPosition,
               width: Math.max(1, bar.rightPosition - bar.leftPosition),
@@ -246,11 +252,11 @@ export const Timeline: React.FunctionComponent<{
       }} />
       {selectedTime && <div className='timeline-window'>
         <div className='timeline-window-curtain left' style={{ width: curtainLeft }}></div>
-        <div className='timeline-window-resizer'></div>
+        <div className='timeline-window-resizer' style={{ left: -5 }}></div>
         <div className='timeline-window-center'>
           <div className='timeline-window-drag'></div>
         </div>
-        <div className='timeline-window-resizer'></div>
+        <div className='timeline-window-resizer' style={{ left: 5 }}></div>
         <div className='timeline-window-curtain right' style={{ width: curtainRight }}></div>
       </div>}
     </div>
diff --git a/packages/web/src/components/treeView.tsx b/packages/web/src/components/treeView.tsx
index 61a944ff9f..9bf6f77b94 100644
--- a/packages/web/src/components/treeView.tsx
+++ b/packages/web/src/components/treeView.tsx
@@ -159,15 +159,15 @@ type TreeItemData = {
 
 function flattenTree<T extends TreeItem>(rootItem: T, selectedItem: T | undefined, expandedItems: Map<string, boolean | undefined>, autoExpandDepth: number): Map<T, TreeItemData> {
   const result = new Map<T, TreeItemData>();
-  const temporaryExpanded = new Map<string, boolean | undefined>();
+  const temporaryExpanded = new Set<string>();
   for (let item: TreeItem | undefined = selectedItem?.parent; item; item = item.parent)
-    temporaryExpanded.set(item.id, true);
+    temporaryExpanded.add(item.id);
 
   const appendChildren = (parent: T, depth: number) => {
     for (const item of parent.children as T[]) {
-      const expandState = expandedItems.get(item.id) ?? temporaryExpanded.get(item.id);
+      const expandState = temporaryExpanded.has(item.id) || expandedItems.get(item.id);
       const autoExpandMatches = autoExpandDepth > depth && result.size < 25 && expandState !== false;
-      const expanded = item.children.length ? expandState || autoExpandMatches : undefined;
+      const expanded = item.children.length ? expandState ?? autoExpandMatches : undefined;
       result.set(item, { depth, expanded, parent: rootItem === parent ? null : parent });
       if (expanded)
         appendChildren(item, depth + 1);