I want to create a WPF window that behaves as a modal dialogue box while at the same time facilitating selected operations on certain other windows of the same application. An example of this behaviour can be seen in Adobe Photoshop, which offers several dialogues that allow the user to use an eyedropper tool to make selections from an image while disabling virtually all other application features.

I'm guessing that the way forward is to create a non-modal, always-on-top dialogue and programmatically disable those application features that are not applicable to the dialogue. Is there an easy way to achieve this in WPF? Or perhaps there's a design pattern I could adopt.