• +/- quasi-logarithmic (damped) scale, eg. is centered at 0. useful for amplitudes etc, like -100, -10, -1, 0, 1, 10, 100 with configurable y to y' fn.
• make arrows a bit more configurable, like allow setting filling, lenght and width
• allow axes with arrows in both directions
• allow 2nd y and 2nd x-axis
• configure color of each axis separately
• allow background-configuration and image
• transparent setting for backgrounds (png etc.)
• allow filling of fn as wipe, configure color at plus-you-name-it, at 0 and at minus-you-name-it
• allow filling with GIVEN #hexcolor
BTW: cool prog!