[WinForms][UIA] Add new internal event to track form's owner change (#18117)

This PR is needed for https://github.com/mono/uia2atk/pull/8

1 files changed, 15 insertions, 0 deletions

diff --git a/mcs/class/System.Windows.Forms/System.Windows.Forms/Form.cs b/mcs/class/System.Windows.Forms/System.Windows.Forms/Form.cs
index 73dff86a6a7..7f032754f70 100644
--- a/mcs/class/System.Windows.Forms/System.Windows.Forms/Form.cs
+++ b/mcs/class/System.Windows.Forms/System.Windows.Forms/Form.cs
@@ -1099,6 +1099,8 @@ namespace System.Windows.Forms {
 							XplatUI.SetOwner(this.window.Handle, IntPtr.Zero);
 						}
 					}
+					// UIA Framework: Raises internal event
+					OnUIAOwnerChanged ();
 				}
 			}
 		}
@@ -3202,6 +3204,7 @@ namespace System.Windows.Forms {
 		static object UIAMenuChangedEvent = new object ();
 		static object UIATopMostChangedEvent = new object ();
 		static object UIAWindowStateChangedEvent = new object ();
+		static object UIAOwnerChangedEvent = new object ();
 
 		internal event EventHandler UIAMenuChanged {
 			add { Events.AddHandler (UIAMenuChangedEvent, value); }
@@ -3218,6 +3221,11 @@ namespace System.Windows.Forms {
 			remove { Events.RemoveHandler (UIAWindowStateChangedEvent, value); }
 		}
 
+		internal event EventHandler UIAOwnerChanged {
+			add { Events.AddHandler (UIAOwnerChangedEvent, value); }
+			remove { Events.RemoveHandler (UIAOwnerChangedEvent, value); }
+		}
+
 		internal void OnUIAMenuChanged (EventArgs e)
 		{
 			EventHandler eh = (EventHandler) Events [UIAMenuChangedEvent];
@@ -3238,6 +3246,13 @@ namespace System.Windows.Forms {
 			if (eh != null)
 				eh (this, EventArgs.Empty);
 		}
+
+		internal void OnUIAOwnerChanged ()
+		{
+			EventHandler eh = (EventHandler) Events [UIAOwnerChangedEvent];
+			if (eh != null)
+				eh (this, EventArgs.Empty);
+		}
 		#endregion	// UIA Framework Events
 		#endregion	// Events
 	}