Fix issue 14422：PropertyGrid's SelectedTab no longer changes when the SelectedObject is assigned

src/System.Windows.Forms/System/Windows/Forms/Controls/PropertyGrid/PropertyGrid.cs

@@ -3710,15 +3710,10 @@ private void SelectViewTabButton(ToolStripButton button, bool updateSelection)
 
     private bool SelectViewTabButtonDefault(ToolStripButton? button)
     {
-        if (button is null)
-        {
-            return false;
-        }
-
         // Is this tab button checked? If so, do nothing.
         if (button == _selectedTab?.Button)
         {
-            button.Checked = true;
+            button?.Checked = true;
             return true;
         }
 
@@ -3755,7 +3750,6 @@ private bool SelectViewTabButtonDefault(ToolStripButton? button)
 
         // Select the first tab if we didn't find that one.
         _selectedTab = _tabs[PropertiesTabIndex];
-        Debug.Assert(_tabs[PropertiesTabIndex].Tab.GetType() == DefaultTabType, "First item is not property tab!");
         SelectViewTabButton(_tabs[PropertiesTabIndex].Button, updateSelection: false);
         return false;
     }

src/test/unit/System.Windows.Forms/System/Windows/Forms/PropertyGridTests.cs

@@ -2360,6 +2360,20 @@ public void PropertyGrid_PropertySort_SetWithHandle_GetReturnsExpected(PropertyS
         Assert.Equal(0, createdCallCount);
     }
 
+    [WinFormsFact]
+    public void PropertyGrid_SelectedObject_SetAfterReplacingDefaultTab_UsesCustomTab()
+    {
+        using PropertyGrid control = new();
+        control.PropertyTabs.RemoveTabType(typeof(PropertiesTab));
+        control.PropertyTabs.AddTabType(typeof(ReplacementPropertyTab), PropertyTabScope.Static);
+
+        using Button selectedObject = new();
+        control.SelectedObject = selectedObject;
+
+        Assert.Equal(selectedObject, control.SelectedObject);
+        Assert.IsType<ReplacementPropertyTab>(control.SelectedTab);
+    }
+
     [WinFormsFact]
     public void PropertyGrid_PropertyTabCollection_AddAndRemoveTabType_Success()
     {
@@ -2382,6 +2396,27 @@ private class TestPropertyTab : PropertyTab
         public override PropertyDescriptorCollection GetProperties(object component, Attribute[] attributes) => throw new NotImplementedException();
     }
 
+    private class ReplacementPropertyTab : PropertyTab, IDisposable
+    {
+        private Bitmap _bitmap;
+
+        public override string TabName => "ReplacementPropertyTab";
+
+        public override Bitmap Bitmap => _bitmap ??= new(10, 10);
+
+        public override PropertyDescriptorCollection GetProperties(object component, Attribute[] attributes)
+            => TypeDescriptor.GetProperties(component, attributes);
+
+        public override PropertyDescriptorCollection GetProperties(ITypeDescriptorContext context, object component, Attribute[] attributes)
+            => TypeDescriptor.GetProperties(component, attributes);
+
+        public override void Dispose()
+        {
+            _bitmap?.Dispose();
+            base.Dispose();
+        }
+    }
+
     [WinFormsFact]
     public void PropertyGrid_SelectedGridItem_SetNull_ThrowsArgumentNullException()
     {