How can Proto design for multiple screens that can be a difficult and time-consuming task.
Is it possible to incorporate "new fluid layout" like in DW for all , desktop, iPad, iphone devices?.
your expert knowledge will be most welcomed
You can do your wireframes for multiple devices and then use the DW media queries for example to display the appropriate content.
Should also note that if you are referrring to Responsive designs, then no it can't be done yet as Proto uses Absolute Positioning for it's placement of divs, etc.
Hopefully that will be something that is coming in the future.