Hi,
In order to share a Roadmap widget use the GetWidgetHyperLink function http://usermanual.clarizen.com/clarizen-functions$GetWidgetHyperLink_Function_Samples
You can definitely hide a milestone from a roadmap. Just click on the milestone icon in the roadmap and change the visibility settings (attached a screenshot).
I am not sure what do you mean in hiding complete/cancelled project - hiding where?
Best,
Tamir
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