Several problems with using the HTML5 launcher on the desktop have been reported upstream:
#1293898: The toolbar cannot be hidden or revealed.
#1294981: Mouse wheel events cannot be caught.
#1294985: Drag events cannot be caught.
I doubt that any of these will be fixed in a timely manner, so for now, the crosswords script provides a better environment.
Several problems with using the HTML5 launcher on the desktop have been reported upstream: #1293898: The toolbar cannot be hidden or revealed. #1294981: Mouse wheel events cannot be caught. #1294985: Drag events cannot be caught.
I doubt that any of these will be fixed in a timely manner, so for now, the crosswords script provides a better environment.