~cartoon/cartoon cycle does not hide backbone

[Elaine Meng]

If I hide and re-show cartoon, the mainchain atoms are still shown. Example:

open 2gbp
color mainchain magenta targ a
(...OK only CA magenta as expected)
~cartoon
cartoon
(...now you can see also magenta N,C,O)
cartoon hide true
(...doesn't do anything, so problem is not because hide was set false)

[Conrad Huang]

This is related to #221.

It looks like the all atoms of selected residue are "shown" by the smart display but the mainchain atoms are hidden by the ribbon. The "~cartoon" command therefore displays all the shown mainchain atoms in those residues now (showing magenta N, CA, C and O). The subsequent "cartoon" command now hides N, C and O, showing the CA where it is connected to a sidechain.

I think this is the correct behavior. Please re-open if you disagree.

[Elaine Meng]

Perfect. Now cartoon hides the mainchain atoms like it is supposed to, and behavior including interaction with smart display is same as in Chimera1.