Allow the user to resize and position the new message window. You can do this in Apple Mail. You resize and position it once and then it opens that way from then on. Composer/Normal is too small and too far to the right. Composer/Maximized is too big and too far to the left. Or add a third Composer medium/center option.

Also when you minimze the mail window the new message window should be there so you can more easily drag and drop photos and documents from your desktop into the message. (It works this way in Apple Mail.)