wxOSX: Fix wxPopupTransientWindow's mouse event handling.

In MacOSX/cocoa, wxPopupTransientWindow needs to do mouse capture handling during OnIdle().
But it's done wrongly when decide whether the mouse is within the popup.
Not fixed with simply checking the mouse pos against the client rect of the popup.

Author: 徐扬斌

src/common/popupcmn.cpp

@@ -451,19 +451,23 @@ void wxPopupTransientWindow::OnIdle(wxIdleEvent& event)
 
     if (IsShown() && m_child)
     {
-        // Store the last mouse position to minimize the number of calls to
-        // wxFindWindowAtPoint() which are quite expensive.
+        // Store the last mouse position
         static wxPoint s_posLast;
         const wxPoint pos = wxGetMousePosition();
         if ( pos != s_posLast )
         {
             s_posLast = pos;
-
-            wxWindow* const winUnderMouse = wxFindWindowAtPoint(pos);
+			
+            // DO NOT use wxFindWindowAtPoint() because if there're multiple top level windows,
+            // it will 'Find the deepest window at the given mouse position in screen coordinates', 
+            // which is not the right one for this logic.
+            auto screen_rect = GetScreenRect();
+            const auto mouse_within_me = (pos.x >= screen_rect.GetTopLeft().x and pos.y >= screen_rect.GetTopLeft().y and
+                pos.x <= screen_rect.GetBottomRight().x and pos.y <= screen_rect.GetBottomRight().y);
 
             // We release the mouse capture while the mouse is inside the popup
             // itself to allow using it normally with the controls inside it.
-            if ( wxGetTopLevelParent(winUnderMouse) == this )
+            if ( mouse_within_me )
             {
                 if ( m_child->HasCapture() )
                 {