Sorry, there is currently no way to do that without changing the code.  If you're up to it, you need to edit the CHIMERA/share/NucleicAcids/__init__.py file where CHIMERA is the directory where Chimera is installed.  In that file, inside the ladder function ('def ladder' on line 1273), you will find a loop (at line 1330) where it first gets the color of each residue in the ladder:
 r0color_kwds = _ribbon_color(r0)
 r1color_kwds = _ribbon_color(r1)
and later there are two drawCylinder() calls.

The "fix" is to add two more lines after fetching the residue colors to override them with the color you want, so those two lines become:
r0color_kwds = _ribbon_color(r0)
r1color_kwds = _ribbon_color(r1)
r0color_kwds['color'] = (.2, .8, .2)
r1color_kwds['color'] = r0color_kwds['color']

Where (.2, .8, .2) are the RGB values of the color you want.

    HTH,

    Greg

On 7/24/2015 11:37 AM, Belle Lin wrote:
Dear Chimera users/developers,

Is there a way to make the DNA ladders a different color than the backbone? I am able to do so when the side (sugar/base) is shown in the "tube/slab" mode, but when I change it to the "ladder" mode I am unable to change the color of the rungs. I have included photos below which hopefully make my question more clear. Thank you in advance for your help!!

Thanks,
Belle Lin

_____________________________________________________________

Able to create: 
Inline image 3

Inline image 2

Trying to create: 
 Inline image 1


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