The problem is that points are not begin plotted, segments are treated as closed polygons and closed polygons are filled (which I can suppress by adding -G- in the header).
Any idea ?
gmt begin test png
gmt coast -R-120/120/-80/80 -JM20c -Bafg -Gantiquewhite -Slightblue -Wthinner,black -Di -A10000
gmt plot tmp.txt
gmt end show
One can mix lines and filled polygons but we must undo previous options when those are not wished anymore. An option in a header remains active through next segments.
You can also change symbols by adding the required -S option to any of your multi-segment headers.
but not sure how to use it. And it also seems that once we set a -G in header all posterior segments will close the lines. At most what can be prevented is to fill it but not the closing.