Request for feature: mac osx - compose mail in tab

Hello, it would be great if composing new mail would be possible in a tab instead of a new window on mac osx. Checking the developer forums, I found out, that this topic has alread been discussed. But I would like to add a point: a great feature of osx is to run apps in fullscreen-mode, that behaves like different desktops. The inability of thunderbird writing an email in a tab, makes this feature practicaly unusable with thunderbird, as every new mail forces me to exit this fullscreen mode, resepctively makes me change the "desktop". Is it really that complicated to implement that feature? Thunderbird is great by the way, and I am very happy it is still maintained! I use it as my only mail-client on my macs. Keep on the good work. Thank you for your attention. Best Alex