Removing node from queue reverted by node add

The current UI allows for some non-intuitive behaviour: in a fully populated four node queue, clicking "remove" (on, say, node 3), triggers a warning message that nodequeue state is not persisted ("Changes made in this table will not be saved until the form is submitted.") but using the autocomplete and "Add content" button to add a fifth node causes the previously removed node to be reinstated (and likely) the node in position 1 to be popped off the queue.

IMO, it's reasonable for a user to expect that "remove" did immediately remove the node (e.g. via XHR), or that clicking the "Add content" button submits the form (fulfilling the action described in the warning message), or that clicking "Add content" is similarly provisional and final nodequeue state requires submission via Save button.