switch from `blur` to `focus` event, and use `target` instead of `relatedTarget`
switch from `blur` to `focus` event, and use `target` instead of `relatedTarget`

re #555, re #557
christianmemije/kolibri,learningequality/kolibri,christianmemije/kolibri,rtibbles/kolibri,mrpau/kolibri,indirectlylit/kolibri,DXCanas/kolibri,mrpau/kolibri,jonboiser/kolibri,DXCanas/kolibri,benjaoming/kolibri,rtibbles/kolibri,mrpau/kolibri,mrpau/kolibri,DXCanas/kolibri,indirectlylit/kolibri,jonboiser/kolibri,jayoshih/kolibri,jonboiser/kolibri,jayoshih/kolibri,learningequality/kolibri,aronasorman/kolibri,lyw07/kolibri,jayoshih/kolibri,MingDai/kolibri,benjaoming/kolibri,benjaoming/kolibri,christianmemije/kolibri,jayoshih/kolibri,MingDai/kolibri,learningequality/kolibri,DXCanas/kolibri,MingDai/kolibri,rtibbles/kolibri,MingDai/kolibri,lyw07/kolibri,aronasorman/kolibri,aronasorman/kolibri,lyw07/kolibri,benjaoming/kolibri,learningequality/kolibri,lyw07/kolibri,aronasorman/kolibri,rtibbles/kolibri,indirectlylit/kolibri,christianmemije/kolibri,jonboiser/kolibri,indirectlylit/kolibri