Update material when reference to shader gets lost

[Helper]

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On 25/11/2012 at 02:39, xxxxxxxx wrote:

User Information:
Cinema 4D Version:   R14 
Platform:   Windows  ;   
Language(s) :       PYTHON  ;

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Hi People.

I have a ShaderData plugin that implements a link field accepting shaders only. It
basically just clones the shader referenced from the link field.

The problem is, that when the source shader is deleted or replaced, the material is not
updated. The link field becomes empty because the referenced shader no longer exists,
but the material still looks like the referenced shader did exist.

Here's a small vid showing the problem: http://www.youtube.com/watch?v=TT4DvGwloWg

How can the material be updated when the referenced shader is eliminated?

Thanks in advance,
NIklas