I'm having trouble on how am going to start this idea of mine. I have an image and I want to plot points on that image. My Idea is to get the X and Y coordinates of the mouse pointer and save it into a text file so that by the time I re-run the program again, the plotted points is still there. But it seems like this is not a good idea since everything will be messed up if I load the program to a computer with different screen size. I was thinking of placing an invisible grid, but looks like this will be tough to do.