# System.Windows.Forms

``` diff
 namespace System.Windows.Forms {
     public class PropertyGrid : ContainerControl, IComPropertyBrowser, IPropertyNotifySink.Interface {
-        public override Image BackgroundImage { get; set; }
+        public override Image? BackgroundImage { get; set; }
-        public GridItem SelectedGridItem { get; set; }
+        public GridItem? SelectedGridItem { get; set; }
-        public object SelectedObject { get; set; }
+        public object? SelectedObject { get; set; }
-        public override ISite Site { get; set; }
+        public override ISite? Site { get; set; }
-        protected ToolStripRenderer ToolStripRenderer { get; set; }
+        protected ToolStripRenderer? ToolStripRenderer { get; set; }
-        public new event EventHandler BackgroundImageChanged;
+        public new event EventHandler? BackgroundImageChanged;
-        public new event EventHandler BackgroundImageLayoutChanged;
+        public new event EventHandler? BackgroundImageLayoutChanged;
-        public new event EventHandler ForeColorChanged;
+        public new event EventHandler? ForeColorChanged;
-        public new event KeyEventHandler KeyDown;
+        public new event KeyEventHandler? KeyDown;
-        public new event KeyPressEventHandler KeyPress;
+        public new event KeyPressEventHandler? KeyPress;
-        public new event KeyEventHandler KeyUp;
+        public new event KeyEventHandler? KeyUp;
-        public new event MouseEventHandler MouseDown;
+        public new event MouseEventHandler? MouseDown;
-        public new event EventHandler MouseEnter;
+        public new event EventHandler? MouseEnter;
-        public new event EventHandler MouseLeave;
+        public new event EventHandler? MouseLeave;
-        public new event MouseEventHandler MouseMove;
+        public new event MouseEventHandler? MouseMove;
-        public new event MouseEventHandler MouseUp;
+        public new event MouseEventHandler? MouseUp;
-        public new event EventHandler PaddingChanged;
+        public new event EventHandler? PaddingChanged;
-        public event EventHandler PropertySortChanged;
+        public event EventHandler? PropertySortChanged;
-        public event PropertyTabChangedEventHandler PropertyTabChanged;
+        public event PropertyTabChangedEventHandler? PropertyTabChanged;
-        public event PropertyValueChangedEventHandler PropertyValueChanged;
+        public event PropertyValueChangedEventHandler? PropertyValueChanged;
-        public event SelectedGridItemChangedEventHandler SelectedGridItemChanged;
+        public event SelectedGridItemChangedEventHandler? SelectedGridItemChanged;
-        public event EventHandler SelectedObjectsChanged;
+        public event EventHandler? SelectedObjectsChanged;
-        event ComponentRenameEventHandler System.Windows.Forms.ComponentModel.Com2Interop.IComPropertyBrowser.ComComponentNameChanged;
+        event ComponentRenameEventHandler? System.Windows.Forms.ComponentModel.Com2Interop.IComPropertyBrowser.ComComponentNameChanged;
-        public new event EventHandler TextChanged;
+        public new event EventHandler? TextChanged;
-        protected virtual PropertyTab CreatePropertyTab(Type tabType);
+        protected virtual PropertyTab? CreatePropertyTab(Type tabType);
-        protected void OnNotifyPropertyValueUIItemsChanged(object sender, EventArgs e);
+        protected void OnNotifyPropertyValueUIItemsChanged(object? sender, EventArgs e);
-        void IComPropertyBrowser.LoadState(RegistryKey key);
+        void IComPropertyBrowser.LoadState(RegistryKey? key);
-        void IComPropertyBrowser.SaveState(RegistryKey key);
+        void IComPropertyBrowser.SaveState(RegistryKey? key);
     }
 }
```

