-      ::TransitionWindow((WindowRef)m_macWindow,kWindowZoomTransitionEffect,kWindowShowTransitionAction,nil);
-      ::SelectWindow( (WindowRef)m_macWindow ) ;
-      // no need to generate events here, they will get them triggered by macos
-      // actually they should be , but apparently they are not
-      wxSize size(m_width, m_height);
-      wxSizeEvent event(size, m_windowId);
-      event.SetEventObject(this);
-      GetEventHandler()->ProcessEvent(event);
+        #if wxUSE_SYSTEM_OPTIONS       //code contributed by Ryan Wilcox December 18, 2003
+        if ( (wxSystemOptions::HasOption(wxMAC_WINDOW_PLAIN_TRANSITION) ) && ( wxSystemOptions::GetOptionInt( wxMAC_WINDOW_PLAIN_TRANSITION ) == 1) )
+        {
+           ::ShowWindow( (WindowRef)m_macWindow );
+        }
+        else
+        #endif
+        {
+           ::TransitionWindow((WindowRef)m_macWindow,kWindowZoomTransitionEffect,kWindowShowTransitionAction,nil);
+        }
+        ::SelectWindow( (WindowRef)m_macWindow ) ;
+        // no need to generate events here, they will get them triggered by macos
+        // actually they should be , but apparently they are not
+        wxSize size(m_width, m_height);
+        wxSizeEvent event(size, m_windowId);
+        event.SetEventObject(this);
+        GetEventHandler()->ProcessEvent(event);