You can't really get seamless wired to wireless roaming.
You have a wired NIC, connected to the wired network, and it gets one IP address.
You have a wireless NIC, connected to the WiFi, and it also gets an IP address, potentially from the same subnet as the wired adaptor.
If your machine has an open TCP connection from its wired IP address and you unplug the wired cable, those connections will drop, as the NIC with that IP address is now offline. Lots of applications will re-connect, but there are no guarantees.