Shader documentation (WPOS definition)

I am running through the following shader documentation:
http://docs.unity3d.com/Manual/SL-VertexFragmentShaderExamples.html

If I try to straight up run some of the shaders provided I run into a few different issues, which makes me wonder if my project is set up differently than expected or if the documentation is outdated. Note that I am using Unity 4.6.3.

1) Issue #1: Custom/WindowCoordinates/Base shader
​

If I divide the WPOS parameter by _ScreenParams in the frag function, the entire poly turns black.
To get the results shown in the screenshot, I need to use the WPOS parameter as is.

return fixed4(sp.xy/_ScreenParams.xy,0.0,1.0); // ==> all black
return fixed4(sp.xy,0.0,1.0); // ==> as shown on screenshot

Same issue with other shaders dividing by _ScreenParams on that page.

2) Issue #2: Custom/WindowCoordinates/Bars shader​

Shader does not compile because of the following error:
Shader error in 'Custom/Bkg Tint+Tile': 'vert': function return value missing semantics at line 15

Thanks.

 

According to this post, WPOS is legacy function and Unity wants us to use VPOS instead:

Hope it helps!