TGraph changes the value of point position

[Wile_E_Coyote]

Try:

Updating using gPad->Modified() and gPad->Update()

Maybe you are facing a bug with the Cocoa version on Mac which was discovered some time ago. After each “Update”, try to add gSystem->ProcessEvents(); (executed once or two times). BTW. When you post “source code” or “output” here, do remember to enclose them into two lines which contain just three characters ``` (see how your post has been edited above).