When an evaluator has a linked pane, the close button in the evaluator should appear as the hidePane16 icon, and its action should be to close and unlink the linked pane.
When the evaluator has no linked pane, the close button should appear with the close icon (as it always does now) and its action should be to close the evaluator.
Thus, to close an evaluator with a linked pane, you click twice -- once to close the linked pane and change the appearance of the button, and again to close the evaluator.
When an evaluator has a linked pane, the close button in the evaluator should appear as the hidePane16 icon, and its action should be to close and unlink the linked pane.
When the evaluator has no linked pane, the close button should appear with the close icon (as it always does now) and its action should be to close the evaluator.
Thus, to close an evaluator with a linked pane, you click twice -- once to close the linked pane and change the appearance of the button, and again to close the evaluator.