Fix: Fixed an issue where opening new columns in Columns View didn't always scroll them into view (#17826)

Author: workbysaran

src/Files.App.Controls/BladeView/BladeView.cs

@@ -150,6 +150,17 @@ private ScrollViewer GetScrollViewer()
 			return _scrollViewer ?? (_scrollViewer = this.FindDescendant<ScrollViewer>());
 		}
 
+		public void ScrollToEnd()
+		{
+			LayoutUpdated += OnLayoutUpdatedScrollToEnd;
+		}
+
+		private void OnLayoutUpdatedScrollToEnd(object sender, object e)
+		{
+			LayoutUpdated -= OnLayoutUpdatedScrollToEnd;
+			GetScrollViewer()?.ChangeView(_scrollViewer.ScrollableWidth, null, null, false);
+		}
+
 		private void AdjustBladeItemSize()
 		{
 			// Adjust blade items to be full screen
@@ -182,7 +193,8 @@ private void ItemsVectorChanged(IObservableVector<object> sender, IVectorChanged
 			else if (e.CollectionChange == CollectionChange.ItemInserted)
 			{
 				UpdateLayout();
-				GetScrollViewer()?.ChangeView(_scrollViewer.ScrollableWidth, null, null);
+				// The following line doesn't work as expected due to the items not being fully loaded yet and thus the scrollable width not being accurate.
+				//GetScrollViewer()?.ChangeView(_scrollViewer.ScrollableWidth, null, null);
 			}
 		}
 	}

src/Files.App/Views/Layouts/ColumnsLayoutPage.xaml.cs

@@ -89,6 +89,8 @@ public void SetWidth(int index)
 
 			var blade = activeBlades[index];
 			blade?.SetWidth();
+
+			ColumnHost.ScrollToEnd();
 		}
 
 		private void ContentChanged(IShellPage p)