Fix Multiple Drag and drop causing NotReturn Method Call

Author: taooceros

Flow.Launcher/ResultListBox.xaml.cs

@@ -92,6 +92,8 @@ private void ListBox_PreviewMouseDown(object sender, MouseButtonEventArgs e)
         private Point start;
         private string path;
         private string query;
+        // this method is called by the UI thread, which is single threaded, so we can be sloppy with locking
+        private bool isDragging;
 
         private void ResultList_PreviewMouseLeftButtonDown(object sender, MouseButtonEventArgs e)
         {
@@ -101,15 +103,16 @@ private void ResultList_PreviewMouseLeftButtonDown(object sender, MouseButtonEve
             path = result.Result.CopyText;
             query = result.Result.OriginQuery.RawQuery;
             start = e.GetPosition(null);
+            isDragging = true;
         }
-
         private void ResultList_MouseMove(object sender, MouseEventArgs e)
         {
-            if (e.LeftButton != MouseButtonState.Pressed)
+            if (e.LeftButton != MouseButtonState.Pressed|| !isDragging)
             {
                 start = default;
                 path = string.Empty;
                 query = string.Empty;
+                isDragging = false;
                 return;
             }
 
@@ -123,15 +126,16 @@ private void ResultList_MouseMove(object sender, MouseEventArgs e)
                 || Math.Abs(diff.Y) < SystemParameters.MinimumVerticalDragDistance)
                 return;
 
+            isDragging = false;
+            
             var data = new DataObject(DataFormats.FileDrop, new[]
             {
                 path
             });
-            DragDrop.DoDragDrop((DependencyObject)sender, data, DragDropEffects.Move | DragDropEffects.Copy);
-
-            App.API.ChangeQuery(query, true);
-
-            e.Handled = true;
+            
+            var effect = DragDrop.DoDragDrop((DependencyObject)sender, data, DragDropEffects.Move | DragDropEffects.Copy);
+            if (effect == DragDropEffects.Move)
+                App.API.ChangeQuery(query, true);
         }
         private void ResultListBox_OnPreviewMouseRightButtonDown(object sender, MouseButtonEventArgs e)
         {