add 2D markers with size in data units

[emmanuelle]

At the moment the size of markers is in plot units, ie markers keep the same size when zooming in or out. It would be useful to have the possibility to have a marker size in data size, ie markers would get bigger on screen when zooming in.

Requested for example in the forum https://community.plotly.com/t/keeping-dot-size-fixed-on-scatterplot/39539.

The equivalent feature for 3D glyphs is documented in #4329

[s4m0r4m4]

The current best solution is to use fig.add_shape(type="circle",...), which is not desirable for large datasets. I would definitely appreciate a way to do this on the scatter plots!

[tsitsimis]

+1 This would be very handy!

[cor1]

+1

[xdev-x]

+1

[alexr314]

+1