buy sale
need not core.OutUIMouseDown
directly do not send mouse msgs to scene but only uicore

timeGetTime

state dir where s0=(0,1) and s2 =
ifd=0
ret s1
else
ret d
endstate

cached step =
if tc < 0.25*Dt
ret 0
elif tc < 0.5*Dt
ret 1
elif tc < 0.75
ret 0
else
ret -1

dictionary<takaku.tuple<int,int,int>, bitmap> pics;