[Paraview] Bug: saving screenshot with screen or print palette resets background color

[Olumide]

> I'm not sure if this has been reported/logged. This bug is easy to 
> reproduce. Here's how to:
> 
> 1. Open a new Paraview scene, and set the background color (to white for 
> example)
> 
> 2. Import or create a VTK object
> 
> 3. Export screenshot with the screen or print palette.
> 
> Result: the Paraview background color is reset to the default value.

Update:
This bug is affects more than just the background color. It also resets 
the wireframe color of a geometric object. Here's how to reproduce it:

1. create an object e.g. sphere primitive

2. set its representation to wireframe, and color to red (or any color 
other than the default)

3. set background to white

4. save screenshot with print palette

Result: the mesh and background are reset to their default colors. In 
addition, the wireframe color of object in the screenshot is black.

Note: this issue affects only objects with wireframe representations in 
a scene. Objects with surface or surface with edges representations in 
the same scene are unaffected, even though the background color is reset.