The news agency Maan reported that the signing of the Fatah-Hamas reconciliation agreement in Cairo is being delayed because of a seating arrangement issue.
According to the report, an argument has broken out over the spot where Hamas politburo chief Khaled Mashaal will sit. According to another report, Palestinian President Mahmoud Abbas has refused to sit next to Mashaal, and demanded to be presented as the Palestinian president instead of the head of his political party.
From other Arabic news sources, it seems to me that Hamas is not accepting Abbas as president of the PA even under this agreement (this has long been their official position, since his official term in office ended.)
Which is just one more indication that this agreement is a sham. Hamas will retain its own security in Gaza and it will be part of the government as much as Hezbollah is part of Lebanon's - enough to veto whatever they don't like but not subservient to it or subject to the PA's laws.