Sticky Window Option? (urxvt specific)

I am setting up urxvt so it appears as my desktop background.

It's all going well so far except for one problem I cannot figure out.

I want this urxvt instance to be ignored by "show desktop" or in other words to be stuck to the desktop in the same way that conky is stuck and is ignored by the show desktop command.

Does anyone have any ideas on how to achieve this?

I cannot see an option in urxvt similar to conky's "sticky" option, nor can I see and option in openbox to make a window "sticky" (I tried actually adding <sticky>yes</sticky> to my rc.xml as a complete guess )

The other alternative might be to have the show desktop action ignore certain windows?

Below are my current configs.

rc.xml section

<application name="urxvt-bg">
  <decor>no</decor>
      <skip_taskbar>yes</skip_taskbar>
      <skip_pager>yes</skip_pager>
  <focus>no</focus>
  <position>
    <x>center</x>
    <y>0</y>
  </position>
  <layer>below</layer>
  <desktop>all</desktop>
<maximized>true</maximized> #Only if you want a full size terminal.
</application>

I run this command when starting the "background" instance of urxvt (this is just overriding some options in my .Xdefaults so may not apply to everyone's setup).

urxvt -name urxvt-bg -borderLess -shading  0 -fading 0% -background rgba:0000/0000/0000/0000