Easy changeover between perspective window and named query or script window

When programming both perspective window and named query window, it's not easy to change over.

Is there any way to float either the named query window or the perspective window, so I don't have to go to the project browser each time I want to look for some information at the other window?

No, not currently. The Designer changes its entire context as you switch between Named Queries, Vision, Perspective, or any of the other top-level project contexts - providing different toolbars and options as you enter each area.

Or can I open two designer sessions but opening the same project at the same time?

Yes, you can do that. Just be aware that as you save in one Designer you will need to update your project in the second Designer due to project changes. There will be a button in the bottom right of the Designer notifying you of the available updated content.