TH2 plot visualisation problem on macOs

[collamaf]

Hi everybody! I have been experiencing this problem since few weeks.
When I try to plot any TH2 histogram, the visualisation appears in a strange way (see picture):
If I connect an external display to my MacBook, and move the plot window to it, as soon as I perform an even slight resize of the window the plot gets its normal appearance, working normally then.
But when I move it back again to the embedded display the opposite happens: at the first resize the look gets “grayed” again.

Has anybody else encountered the problem and maybe solved it? It is pretty annoying when you don’t have an external display available…

Ps: I tried to identify some correlation between the appearance of the bug and any update to my system, but I did not find any

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ROOT Version: 6.15/01
Platform: macOs 10.14.2, MacBook Pro 15’’ retina (pre Touch Bar)
Compiler: Apple LLVM version 10.0.0 (clang-1000.11.45.5)
Target: x86_64-apple-darwin18.2.0

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[couet]

By default the marker style to draw a scatter plot is “1” and it is drawn as a single pixel. On retina screens one single pixel is really small that’s why you get this greyish effect. To bypass this you can use bigger dots. For instance marker style 6:

h2->SetMarkerStyle(6);

Also the pseudo-scatter plot to render TH2 is not the best you can choose. Option COL or BOX are much better.