Hi, The attached file includes my own Demonstration and one found in Wolfram, both created by Mathematica 10 and worked perfectly. When I tried to use it with the new Mathematica 11, it does not work properly (it seems to be the "Epilog" that creates the problem). I would be happy if somebody can solve the issue!
Additionally you can add Dynamic to the Epilog so the whole Plot does not need to be regenerated to change Point position:
Dynamic
Epilog
Plot
Point
Manipulate[ Plot[Sin[x], {x, 0, 10}, Epilog -> {AbsolutePointSize@7, Dynamic@Point[{a, Sin[a]}]}], {a, 0, 10} ]
Thanks Very much Kyle! The first alternative was still "Red", while the second alternative worked exactly as it worked with Mathematica 10.3 last year. I expected the new version would simplify things...
Christos
