>In WPF, can I create a Window/Form and have other windows inherit from that master form? How?
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>Can this also be done with the controls like buttons and grids?
It can be done but I think you can see from the rest of the comments, that this is not something that works well in WPF.
If all you want to do is alter the appearance of the controls, you would use styles and templates for that.
If you need more than that, give an example of what you need and we can probably help you out with it.