Shabbat 91: On Fusion, Theft, and Shabbat Prohibitions

In daf 91(b), we learned a new Mishna: one who carries out food from his house on Shabbat and placed it on the threshold of the door, whether it is carried out from that place into the public domain by himself or another, he is exempt because he did not perform his prohibited labour of carrying from one domain to another.  If one placed a basket full of fruit on the outer threshold, which is in the public domain, and part of the basket stayed inside, one is exempt until he carries out the entire basket even though most of the fruit is outside in the public domain.

The rabbis first discuss the nature of a threshold.  Is it part of the public domain at all, or is it part of the karmelit or a colonnade?  was the basket filled with long vegetables like cucumbers and gourds which might be mostly outside of the basket?  It seems that all that is in the basket fuses together for the sake of carrying.  Or does it?  Rav Beivai bar Abaye objects based on the learning about stealing a purse on Shabbat.  One is still liable for theft.  One who drags the purse and exits the private domain is except from paying for a theft because he is not carrying on Shabbat.  It is only when the purse leaves the public domain that one is charged with theft and prohibitions of Shabbat.  The prohibitions of theft precede the prohibitions of Shabbat, and one is not liable until the entire purse enters the public domain.