A method is provided for forming a porous metal catalyst on a substrate for nanotube growth in an emissive display. The another structural color obtained by the structural color change is not reversed to the original structural color. This is because that CLC as one of components of CALL in an amount \xd7\u0394V of the potential change of the pixel electrode caused by the potential change of the supplemental capacitance line changes. The pocket is adapted to store at least one of the accessories. The printhead unit includes an ink supply unit defining a plurality of ink channels for transporting respective types of ink.