diff --git a/packages/devtools_app/lib/src/config_specific/flutter/import_export/import_export.dart b/packages/devtools_app/lib/src/config_specific/flutter/import_export/import_export.dart
index 1199fa0289e..1b916d7aa39 100644
--- a/packages/devtools_app/lib/src/config_specific/flutter/import_export/import_export.dart
+++ b/packages/devtools_app/lib/src/config_specific/flutter/import_export/import_export.dart
@@ -31,21 +31,30 @@ class ImportController {
     this._pushSnapshotScreenForImport,
   );
 
+  static const repeatImportTimeBufferMs = 500;
+
   final void Function(String screenId) _pushSnapshotScreenForImport;
 
   final NotificationService _notifications;
 
-  bool importing = false;
+  DateTime previousImportTime;
 
   // TODO(kenz): improve error handling here or in snapshot_screen.dart.
   void importData(Map<String, dynamic> json) {
-    if (importing) return;
-    importing = true;
+    // Do not allow two different imports within 500 ms of each other. This is a
+    // workaround for the fact that we get two drop events for the same file.
+    final now = DateTime.now();
+    if (previousImportTime != null &&
+        (now.millisecondsSinceEpoch - previousImportTime.millisecondsSinceEpoch)
+                .abs() <
+            repeatImportTimeBufferMs) {
+      return;
+    }
+    previousImportTime = now;
 
     final isDevToolsSnapshot = json[devToolsSnapshotKey];
     if (isDevToolsSnapshot == null || !isDevToolsSnapshot) {
       _notifications.push(nonDevToolsFileMessage);
-      importing = false;
       return;
     }
 
@@ -54,8 +63,6 @@ class ImportController {
     offlineDataJson = json;
     _notifications.push(attemptingToImportMessage(activeScreenId));
     _pushSnapshotScreenForImport(activeScreenId);
-
-    importing = false;
   }
 }
 
diff --git a/packages/devtools_app/lib/src/flutter/theme.dart b/packages/devtools_app/lib/src/flutter/theme.dart
index 86c2c161e0e..9de5e836f57 100644
--- a/packages/devtools_app/lib/src/flutter/theme.dart
+++ b/packages/devtools_app/lib/src/flutter/theme.dart
@@ -156,7 +156,9 @@ Color titleSolidBackgroundColor(ThemeData theme) {
   return theme.isDarkTheme ? devtoolsGrey[900] : devtoolsGrey[50];
 }
 
-final chartBackgroundColor = ThemedColor(Colors.grey[50], Colors.grey[850]);
+// This is the same as Theme.of(context).scaffoldBackgroundColor, but we use
+// this in places where we do not have access to the context.
+final defaultBackgroundColor = ThemedColor(Colors.grey[50], Colors.grey[850]);
 const chartAccentColor = ThemedColor(Color(0xFFCCCCCC), Color(0xFF585858));
 const chartTextColor = ThemedColor(Colors.black, Colors.white);
 
diff --git a/packages/devtools_app/lib/src/memory/flutter/memory_chart.dart b/packages/devtools_app/lib/src/memory/flutter/memory_chart.dart
index 53d82745bdf..92a71a04393 100644
--- a/packages/devtools_app/lib/src/memory/flutter/memory_chart.dart
+++ b/packages/devtools_app/lib/src/memory/flutter/memory_chart.dart
@@ -278,7 +278,7 @@ class MemoryChartState extends State<MemoryChart> with AutoDisposeMixin {
           ..textSize = 2.0;
 */
       },
-      backgroundColor: chartBackgroundColor,
+      backgroundColor: defaultBackgroundColor,
       doubleTapToZoomEnabled: false,
       // TODO(terry): For now disable zoom with double-click.
       pinchZoomEnabled: false,
@@ -342,7 +342,7 @@ class MemoryChartState extends State<MemoryChart> with AutoDisposeMixin {
           ..textSize = 2.0;
 */
       },
-      backgroundColor: chartBackgroundColor,
+      backgroundColor: defaultBackgroundColor,
       // TOD(terry): Disable zoom via double-click. Consider +/- button
       //             for a controlled zoom in/zoom out.
       scaleXEnabled: false,
diff --git a/packages/devtools_app/lib/src/timeline/flutter/timeline_flame_chart.dart b/packages/devtools_app/lib/src/timeline/flutter/timeline_flame_chart.dart
index 11f0dfc6801..40cd9ae3bea 100644
--- a/packages/devtools_app/lib/src/timeline/flutter/timeline_flame_chart.dart
+++ b/packages/devtools_app/lib/src/timeline/flutter/timeline_flame_chart.dart
@@ -626,7 +626,7 @@ class TimelineGridPainter extends CustomPainter {
         constraints.maxWidth,
         math.min(constraints.maxHeight, rowHeight),
       ),
-      Paint()..color = chartBackgroundColor,
+      Paint()..color = defaultBackgroundColor,
     );
 
     // Paint the timeline grid lines and corresponding timestamps in the flame
diff --git a/packages/devtools_app/lib/src/timeline/flutter/timeline_screen.dart b/packages/devtools_app/lib/src/timeline/flutter/timeline_screen.dart
index 5dab18b420b..a44254b7b4a 100644
--- a/packages/devtools_app/lib/src/timeline/flutter/timeline_screen.dart
+++ b/packages/devtools_app/lib/src/timeline/flutter/timeline_screen.dart
@@ -111,7 +111,7 @@ class TimelineScreenBodyState extends State<TimelineScreenBody>
 
     // Refresh data on page load if data is null. On subsequent tab changes,
     // this should not be called.
-    if (controller.data == null) {
+    if (controller.data == null && !offlineMode) {
       controller.refreshData();
     }
 
@@ -181,7 +181,7 @@ class TimelineScreenBodyState extends State<TimelineScreenBody>
         timelineScreen,
         if (loadingOfflineData)
           Container(
-            color: Colors.grey[50],
+            color: Theme.of(context).scaffoldBackgroundColor,
             child: const Center(
               child: CircularProgressIndicator(),
             ),