Added simple test if flipping (updating) a window is necessary.
Added simple test if flipping (updating) a window is necessary.

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