Here's what I've got so far:

Each Patern ... cell in Form 1 and Form 14 has a Rectangle defined like this:
var rightThickness = headGrid.ColumnDefinitions.Count == subGroupsCount ? 0 : 1;
var rect = new Rectangle() {
Stroke = Brushes.Black,
//StrokeThickness = new Thickness(0, 1, rightThickness, 0);
StrokeDashArray = { 4d, 4d},
SnapsToDevicePixels = true
};
initially, I started with Border BUT I couldn't find a way to use Dashed stroke in that SO ended up with Rectangle approach. Border on the top of the Rectangle in both Forms is alright BUT it looks odd on the sides because the adjacent Rectangles' stoke on sides overlaps.
How to remove the border from sides?



