I'd like to suggest providing VLAN ID at node editing, table.
There at subnet tree is still a VLAN information visible at column in the right pane, except the leaf one, where IP addresses are visible in the right pane.
It should be very handy to view VLAN ID either somewhere at table header (should be setable on/off). Something like at the attached image:
Or add a view column to every IP address to show apropriate VLAN,
