The Transpose dialog is only available from the menu. Please add a command-key shortcut to open the dialog.
The dialog itself should also default to its last setting. The dialog should also not be so large with so much empty space.
I read in the FAQ:
How do I transpose my music into a different key?
From v1.0.10 you can use Write > Transpose. You can also move notes by a diatonic step using Alt+up/down arrow, but this will not change the key of the music.
Adding the Shift key transposes chromatically. Please add that info to the FAQ.
Please also note that searching for “transpose” in Dorico Help brought up 0 results.