If I had two PF_Param_LAYER parameters and a button, and wanted to copy the choice in the first PF_Param_LAYER to the second when I clicked the button, how could this be done?
(I'm not worried about how to make the button work -- I've figured that out.) There seems to be no equivalent to PF_Param_POPUP's 'value' property, to get then set.
I've tried rolling my own layer parameter, but I got unstuck when trying to get the pixels from the layer (and some other problems when changing/adding/deleting layers).