WM: Fix double registration of parent window.
WM: Fix double registration of parent window.

jcdubois/DirectFB,kevleyski/directfb,djbclark/directfb-core-DirectFB,kaostao/directfb,jcdubois/DirectFB,mtsekm/test,dfbdok/DirectFB1,jcdubois/DirectFB,kaostao/directfb,dfbdok/DirectFB1,Distrotech/DirectFB,mtsekm/test,sklnet/DirectFB,deniskropp/DirectFB,deniskropp/DirectFB,kaostao/directfb,deniskropp/DirectFB,deniskropp/DirectFB,DirectFB/directfb,Distrotech/DirectFB,dfbdok/DirectFB1,DirectFB/directfb,djbclark/directfb-core-DirectFB,DirectFB/directfb,kevleyski/DirectFB-1,kevleyski/DirectFB-1,kevleyski/DirectFB-1,kevleyski/directfb,Distrotech/DirectFB,mtsekm/test,sklnet/DirectFB,lancebaiyouview/DirectFB,sklnet/DirectFB,kevleyski/directfb,kevleyski/directfb,djbclark/directfb-core-DirectFB,kevleyski/DirectFB-1,sklnet/DirectFB,lancebaiyouview/DirectFB,lancebaiyouview/DirectFB,djbclark/directfb-core-DirectFB,lancebaiyouview/DirectFB