I have a 'constant' node within a group.
Constant 'extent' is set to 'Format'.
I pick the 'FormatChoice' pulldown menu to bring it to the group's user parameters.
Exported as a PyPlug.
When PyPlug is loaded, the format menu actually doesn't change the constant format.
When looking at the constant node within the PyPlug, the FormatChoice menu has just disapeared from the constant UI.
To make it reappear, I have to change the 'extent' to any other choice, and then reselect 'Format'.