AnD4D Duh, I never even thought to look there.
I can confirm that this is a matter of inaccuracy. See the following test capx. I replaced the Tilled Background walls with single sprites and there are gaps between them.
zenox98 You are right. There aren't any color options in expressions. Perhaps they are not implemented yet..?
AnD4D Why don't you elaborate on how do you wish the plugin to be improved? Perhaps there is some workaround or Ashley could enhance it in future releases.