The question is :
in the PAST, in my Flash IDE, the rect *WAS* place to "0,0" as its *left-root* to the left root of the scene.
but NOW, the rect *IS* place to "0,0" as its *Center* to the left-root of the scene
I don't know why there's difference between PAST and NOW.
Did I make any action in the IDE , a key-press , or some wrong click in any settings pannel , I've made Flash for 3 years , though my native language is not English , I think i am familar enough with this-English-version of Flash. But this time I really have no idea. 😦