config.txt

true (Always on top? true or false.)
true (Transparent background? true or false. Supported by Windows Vista and later.)
0 0 0 (Background color. Range for values is [0,1])
48 (Width of images in pixels)
48 (Height of images in pixels)
100 (Maximum number of inputs to display at once)
d left img/left.png (A mapping from a direction to the image to display for it. Image file paths cannot have spaces))
d right img/right.png
d up img/up.png
d down img/down.png
d upleft img/upleft.png
d upright img/upright.png
d downleft img/downleft.png
d downright img/downright.png
d center img/center.png
b 0 img/lp.png (A button input. The number is the button index, followed by either a direction or an image file to display for it.)
b 3 img/mp.png
b 5 img/hp.png
b 1 img/lk.png
b 2 img/mk.png
b 7 img/hk.png
h left left (A HAT input, which is the d-pad on many controllers. First is the direction on the controller, then the direction or image it maps to.)
h right right
h up up
h down down
a 0 0 -0.5 left (An axis input. First is the axis index, second the rest postion, third the trigger position, and last is the direction or image it maps to.)
a 0 0 0.5 right
a 1 0 0.5 down
a 1 0 -0.5 up