recommend a graphics library for plotting by the pixel?

I'd like to create a window with a "pause" button and a large plotting
area, in which I'd like to draw a polygon, detect the pixel
coördinates of a mouse click, and then start setting the colors of
pixels by (x,y) coördinates. (This is just for my own amusement, to
play with some formulas for generating fractals using random numbers.)

There seems to be a large number of different python GUI libraries,
and I wonder if someone can recommend the easiests one to learn for
this purpose? (The only python graphics library I've used is PyGame,
which I don't think is the way to go here.)

In the 1970s, people began receiving utility bills for
-£999,999,996.32 and it became harder to sustain the
myth of the infallible electronic brain. (Stob 2001)