Hi @BambOoxX,

I think I'm mostly done reviewing this PR but can you help me understand the intent behind this modifications to scatter plots?

public double LineWidth
{
    get => IsHighlighted ? _lineWidth * HighlightCoefficient : _lineWidth;
    set { _lineWidth = value; _markerLineWidth = (float)value / 2; _markerSize = (float)value * 2; }
}

It seems a little strange to me that changing the LineWidth (part of IHasLine) will secretly change MarkerLineWidth (part of IHasMarker). I'm going to remove that part of the setter, but let me know if there's a good reason for it to be there and I may put it back 👍

EDIT: I'm going to merge but feel free to continue the discussion here or open a new PR if you have suggestions

This landed in an awesome spot, thanks so much @BambOoxX!

var plt = new ScottPlot.Plot();

double[] ys1 = DataGen.Sin(30);
var cmap1 = ScottPlot.Drawing.Colormap.Viridis;

double[] ys2 = DataGen.Cos(30);
var cmap2 = ScottPlot.Drawing.Colormap.Turbo;

for (int i = 0; i < ys1.Length; i++)
{
    double frac = i / (ys1.Length - 1f);

    var circle = plt.AddMarker(i, ys1[i]);
    circle.MarkerShape = MarkerShape.openCircle;
    circle.MarkerSize = i + 5;
    circle.MarkerLineWidth = 1 + i / 2;
    circle.MarkerColor = cmap1.GetColor(1 - frac, .8);

    var triangle = plt.AddMarker(i, ys2[i]);
    triangle.MarkerShape = MarkerShape.openTriangleUp;
    triangle.MarkerSize = i + 5;
    triangle.MarkerLineWidth = 1 + i / 4;
    triangle.MarkerColor = cmap2.GetColor(frac, .8);
}

The idea behind changing the marker properties when changing the line width is only to preserve consistency. The main point is that if you draw a thick line to make it very visible, ans that it has markers, you probably want to see the markers pretty well too.
But that feature is really not mandatory

In a more marker-centric context, it could be interesting that setting the marker size sets the marker line width because large markers with thin lines look correct but small markers with thick lines are very distorded