Made access to the wnd struct thread-safe.

diff --git a/windows/x11drv/event.c b/windows/x11drv/event.c
index 46d9607..3e38071 100644
--- a/windows/x11drv/event.c
+++ b/windows/x11drv/event.c
@@ -1205,6 +1205,8 @@
       if( p_data ) TSXFree(p_data);  
       
     } /* WS_EX_ACCEPTFILES */
+
+  WIN_ReleaseWndPtr(pDropWnd);
 }
 
 /**********************************************************************
@@ -1349,6 +1351,7 @@
 			 (WPARAM16)hDrop.h16, 0L );
 	}
       }
+      WIN_ReleaseWndPtr(pDropWnd);
     }
     if( p_data ) TSXFree(p_data);  
   }
@@ -1413,9 +1416,11 @@
 void EVENT_MapNotify( HWND hWnd, XMapEvent *event )
 {
   HWND hwndFocus = GetFocus();
+  WND *tmpWnd = WIN_FindWndPtr(hwndFocus);
   
   if (hwndFocus && IsChild( hWnd, hwndFocus ))
-    X11DRV_WND_SetFocus( WIN_FindWndPtr( hwndFocus ) );
+      X11DRV_WND_SetFocus(tmpWnd );
+  WIN_ReleaseWndPtr(tmpWnd);
   
   return;
 }