Should modal dialogs be movable?

We use modal dialogs in a web application for actions that require the users to take an action, like log in or configure something before being able to proceed.

We fixed a few layout issues and now have them automatically centered and sized. They can no longer be moved by the user as part of the interaction.

I have mixed feeling about this:

• on the one hand it is nice to be able to move them out of the way

• but on the other hand, the whole point of the dialog is to command attention and moving it out of the way seems to indicate a wrong use case

so..

Should modal dialogs be movable by the user?