Add wxActivateEvent::GetActivationReason().

This method is implemented for wxMSW-only currently and allows to check
whether the window is being activated by a mouse click or in some other way
there.

Closes #15516.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@74915 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

interface/wx/event.h

@@ -2976,16 +2976,46 @@ public:
 class wxActivateEvent : public wxEvent
 {
 public:
+    /**
+        Specifies the reason for the generation of this event.
+
+        See GetActivationReason().
+
+        @since 3.0
+    */
+    enum Reason
+    {
+        /// Window activated by mouse click.
+        Reason_Mouse,
+        /// Window was activated with some other method than mouse click.
+        Reason_Unknown
+    };
+
     /**
         Constructor.
     */
     wxActivateEvent(wxEventType eventType = wxEVT_NULL, bool active = true,
-                    int id = 0);
+                    int id = 0, Reason ActivationReason = Reason_Unknown);
 
     /**
         Returns @true if the application or window is being activated, @false otherwise.
     */
     bool GetActive() const;
+
+    /**
+        Allows to check if the window was activated by clicking it with the
+        mouse or in some other way.
+
+        This method is currently only implemented in wxMSW and returns @c
+        Reason_Mouse there if the window was activated by a mouse click and @c
+        Reason_Unknown if it was activated in any other way (e.g. from
+        keyboard or programmatically).
+
+        Under all the other platforms, @c Reason_Unknown is always returned.
+
+        @since 3.0
+    */
+    Reason GetActivationReason() const;
 };