Platform: improve documentation of redraw() function.
Platform: improve documentation of redraw() function.

Make it clear that it's possible and non-harmful to call it from
drawEvent() itself.

MiUishadow/magnum,ashimidashajia/magnum,ashimidashajia/magnum,DerThorsten/magnum,MiUishadow/magnum,DerThorsten/magnum,ashimidashajia/magnum,DerThorsten/magnum,DerThorsten/magnum,MiUishadow/magnum,MiUishadow/magnum,MiUishadow/magnum,ashimidashajia/magnum,DerThorsten/magnum,MiUishadow/magnum,ashimidashajia/magnum