[ase-users] How to check if a POSCAR file has constraints?

[fabian]

Dear all,

I want to check if a certain POSCAR file has constraints or not.

I tried it like this:

atoms=read(FILENAME)

if atoms.constraints is None:

     pass

else:

      do something

but this does not work it seems. Even if no constraints are present i 
still come out of the else statement.

On a side not...what library is ASE using to display the ase gui ? I 
have no menu entrys and the gui is broken
under ubuntu artfull.

All the best

fabian