A controlled-impedance printed circuit board (PCB) design program allows interactive movement of features from one of the vertically-stacked layers of the design to another layer in a graphical interface. The movement either moves a region of a layer of the PCB design, or moves an entire layer in a layer-swapping operation. The program computes modified widths of circuit traces of the first layer of the controlled-impedance printed circuit board design according to an impedance control value of the controlled-impedance printed circuit board design and according to a new position of the circuit traces caused by a movement of the features of the first layer to the second layer. The program also checks for violation of reference plane requirements for critical signals and warns the designer if such a violation is present.