GlobalResources are not expected to see resources defined in a Page.

The look up for resources is performed from the node where it is used up the view tree, if not found, then it searches in the application resources (GlobalResources + merged dictionaries).

For example, if I have a Page like this:

<Page
  xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
  xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml">
  <Grid>
    <Button/>
  </Grid>
</Page>

And I want to use a resource in the Button, the resource lookup will search in this order:

1. In Button.Resources + merged dictionaries
2. In Grid.Resources + merged dictionaries
3. In Page.Resources + merged dictionaries
4. In Application Resources (GlobalResources + merged dictionaries)

It never goes on the opposite direction.

Anyway, what happens in the video is in fact a bug, because a SolidColorBrush defined at the Page level, should be able to use a Color resource defined at GlobalResources.

It was also not my expectation that a GlobalResources dictionary would be able to access a Page's Resources; I was a bit confused when transcribing the note from the meeting. I'll amend the ticket to revolve around the bug you're describing instead. Thanks Sergio!

Correcting Description and creating new repro steps for the new situation.

These exact repro steps are working for me, even as far back as 0.1.266.
I was unable to reproduce with these steps.

Closing this one, unable to repro - appears to be fixed!