I don't understand the implications, but that would be:

http://source.squeak.org/trunk/Morphic-laza.421.mcz

==================== Summary ====================

Name: Morphic-laza.421
Author: laza
Time: 10 April 2010, 10:11:13.657 am
UUID: bdb40d75-5c3c-ef4b-8af6-5aba1fc537fc
Ancestors: Morphic-ar.420

Prevent FlapTabs to have floats as bounds after a change of the Squeak
window. This sometimes made FlapTabs leave "gribbles" on the screen
while moving them.

Addressing http://bugs.squeak.org/view.php?id=6536



2013/2/12 Stéphane Rollandin <lecteur at zogotounga.net>:
> Still working on porting Scratch to 4.4, I stumbled into a weird display bug
> which I eventually fixed after hours of unpleasant wandering by reverting
> the laza 2010 version of Morph>>position: to the previous wiz version of
> 2004.
>
> The change amounts to replacing
>
>         delta := (aPoint - bounds topLeft) rounded.
>
> with
>
>         delta := aPoint asNonFractionalPoint - bounds topLeft.
>
>
> Hence my question: does someone knows the reason for the 2010 change ?
>
> Stef
>