There's an option included for transferring weight maps from an object to another, under the "Group" dropdown menu, to enable the user to transfer the "Active" group from the source object. That doesn't work.
Exact steps for others to reproduce the error
1- Create a source and destination mesh objects.
2- Create more than one vertex group on some or all of the vertices on the source object and select only one vertex group, in order to make it the active group.
3- Shift select the destination.
4- Enter weight paint mode and invoke the Transfer Weights command.
5- Select the "Active Group" from the Group menu.
6- Nothing is transferred... Only every vertex group gets transferred, and it's a real hassle having to clean up 10s of vertex groups one by one every time...