[pstricks] How can I make a double line with no color in between?

[Herbert Voss]

Am 23.09.2016 um 18:36 schrieb Luis Sequeira:
>
>> On 23 Sep 2016, at 17:26, pstricks-request at tug.org wrote:
>>
>> \documentclass[a4paper,12pt]{article}
>> \usepackage{pst-node}
>> \begin{document}
>>
>> \begin{pspicture}[showgrid](4,4)
>> \pnodes{A}(0,0)(0,4)(4,4)(4,0)
>> \ncline[doubleline,doublecolor=blue,linecolor=red,linewidth=3mm]{A0}{A2}
>> \ncline[doubleline,doublecolor=blue,linecolor=red,linewidth=3mm,strokeopacity=0.5]{A1}{A3}
>> \end{pspicture}
>>
>> \end{document}
>
>
> Thanks for the quick reply, but strokeopacity affects the the (red) lines ; I would like to be able to change the opacity of the blue area between the lines
> (to make it transparent).

No, it affects the red _and_ the inner blue line, as can be seen in the
attached image.

> Is there some parameter that controls the opacity of that area between the lines?

It is not possible to set opacity only the inner line.

Herbert