[itsme]

I really like the transpose UI of Musescore Songbook. It is very fast and intuitive.
A tap on the "##" icon opens that little window shown in the screenshot. Tapping ">" transposes up, tapping "<" transposes down, which is endless, not limited to a number of steps. "Original" returns to the original key. The letters show the main key of the song as given by the key signature (the sharps or flats at the beginning of the first line), the bigger one "D" shows the major key for the sample song (two sharps), the smaller one "B" is the enharmonic minor, "Bm" would be more clear.
Important for me is, that it is topmost in the UI, just one tap away from the current song. In case of a session very fast to be reached in case a different key is requested.
The sliders in MSP are not the best UI element for setting the key, the "Key:" slider can easily be confused with the "Transpose:" slider and the effective key is shown very small and hard to find.
It would be great if such a transposing window would exist and could be configured to the floating toolbar or a touch action.