I would very much like to be able to drag the compose window separately from the main window. It is often necessary to reference a recent or past email when composing a new one. It would be helpful if this worked like Gmail's "popout" feature so the compose window could be positioned wherever necessary including on a second screen.

must-have... compared to all other email clients...

Gmail has had a "popout window" feature on their email web clients for years, where the Compose window will be recreated in it's own browser window. It's incredibly useful! It's a standard feature of desktop email clients due to its usefulness. Please add this feature!

Have it float independent of the main window of the app. The bottom of the compose window may not be visible or reachable if the Windows app window is not in full screen mode.

Being able to float the compose window would be very useful. Move the compose window next to an other window with information to be referenced, move the window to another work space, clicking on share by email and having the compose window pop up, etc.

Having it constrained is frustrating and a barrier to switching to the desktop app permanently.

It seems odd that the Compose window blocks the most recent message in an email thread. Having to minimize/maximize the Compose window to read the message is annoying. Either allow the Compose window to move around the screen, or provide an option to "embed" the Compose window below the most recent email. Thanks for your time, I appreciate the devs' hard work.

Seconded. This is *very* annoying and it shouldn't be difficult to make it movable