[subwindows] Implemented sub window focus handling.
[subwindows] Implemented sub window focus handling.

- subwindows can have focus within toplevel windows (by app)
- focus on subwindows restored when toplevel gets focus

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