No, my decanter is not designed to contain carbonation. Dealing with the sediment in suspension was one of the reasons I put the rest of this beer in the decanter in the first place. When I pour later, it will be much cleaner, because the sediment in suspension will have settled to the bottom.
I was thinking about that priming sugar too. If the decanter is sitting out at room temp, the priming sugar is definately going to ferment (though not carbonate the beer like in a bottle). If i put the decanter in the fridge, fermentation should cease, and I will just have a decanter full of cool, fresh, apricot IPA.
I was just wondering about aging this beer further in this decanter. It doesn't have a sealed opening, but I was able to easily cover the opening with plastic wrap. This should give the beer enough room to covert remaining sugars (and that priming sugar), and keep out bugs, extra bacteria, etc.