Wpf popups or modal windows as user entry screens?

I am building an application which has multiple user entry screens. I would like to know if there are advantages/disadvantages of using wpf popups r开发者_JAVA技巧ather than modal windows? I am using mvvm-light.

I have noticed that popups are being used extensively in touch applications (eg iPad).

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The issue is really one of Desktop vs. Web applications. Popups in Silverlight (or other touch apps) involve having only one real window to work with (the mobile surface, or the web browser). If you are writing a desktop app, then modal windows will probably match user expectations better as Popups cannot leave the parent window.

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pop ups are nice but are very difficult to control. In our apps we are using adorners to be 'pop-up' editors - we have created a control that can hold any other control and display it in the adorner layer of the main window. This allows to do things such as having 1 control appear next to another yet still have the other control in use or we can grey out the background and force focus to the new control and not allow any other control to be used until the 'ok' button is pressed. If you Google for adorners in wpf you will find a lot of excellent articles.