I don't think it's possible. The only way I know of to specify a list of items for a provided property is to use an enum. But there's no way to tell the control to use a different type of enum based on a certain selection.
I wrote an article a while back about an ExtenderProvider that I created to add spell-checking to textboxes. I did have custom drop-down lists that were populated dynamically, but they were on actual properties, not provided properties. (in my code, see
Property Language )
I don't see any way that you can do that. In fact, I would even question why you would want to do that. Provided properties do not give you a lot of control of how they are shown or what they can contain.
But, if you're curious about what I did, you can get my source code and there's a brief explanation on how to do dynamic design-time selection. (
NHunspellTextBoxExtender[
^])
[Fixed the link...seems to keep removing the x from aspx]
The only suggestion that I would have would be to have two provided properties. One for Country and one for food.
When the user selects Country in the property for the extender, then it uses the selection in the Country provided property and ignores anything that was selected in the Food provided property.
The issue, like I said, is that to provide a list of options to the designer, you would have to create an enum and then set that property type as that enum. But, you can't change the type to a different enum dynamically, which is why, AFAIK, you can't do what you're wanting to do.
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