FL Studio support custom layouts for the "typing keyboard to piano keyboard" feature, and I made one to represent the top four rows of an accordion! The left-hand bass side of the accordion (the stradella bass system) is laid out to make playing roots of chords and common chords very easy, and it's laid out using the circle of fifths to make the common chords (V and IV) very accessible. Here is my favorite accordion fingering chart: http://accordionscanada.com/bassrangev3.jpg
Accordion 1:
- The 12345 row is the third of the chord row
- The QWERTY row is the main root chord row - the Y key is C
- The ASDFG row is the major chord row
- The ZXCVB row is the minor chord row
Accordion 2: