Changing the colormap

  If a window has multiple colormaps, you can add keyboard
  or button bindings to Mwm to switch to the next or previous
  colormap.  The functions to switch to the next and previous
  colormap are f.next_cmap and f.prev_cmap.

  For example, to specify Alt Shift F10 to move to the next
  colormap,

  1.  Add this line to the keyboard bindings in your resource
      configuration file.

      Alt  Shift<Key>F10  root|icon|window   f.next_cmap

  2.  Restart Mwm.