Transpose notes in a selection and force specified scale (or a custom one). You can also try to find to what scale and key selected notes belong to.
When Y is checked, only notes that match selected scale are transposed. When N i checked, only notes that do not match are transposed. When both are checked all notes are transposed.
If sequencer selection is checked, notes are transposed in multiple patterns selected in the sequencer.
The tool can be found in the right click menu of the pattern editor. There are also keyboard shortcuts available.