3-pixel line
Here is a 3-pixel wide line that I use as a route line between points on the map:
form5.FLine(Point(i).x ,Point(i).y ,Point(i+1).x,Point(i+1).y ,RGB(RTL.R,RTL.G,RTL.B))
form5.FLine(Point(i).x+1 ,Point(i).y ,Point(i+1).x+1,Point(i+1).y ,RGB(RTL.R,RTL.G,RTL.B))
form5.FLine(Point(i).x-1 ,Point(i).y ,Point(i+1).x-1,Point(i+1).y ,RGB(RTL.R,RTL.G,RTL.B))
form5.FLine(Point(i).x , Point(i).y+1 ,Point(i+1).x,Point(i+1).y+1 ,RGB(RTL.R,RTL.G,RTL.B))
form5.FLine(Point(i).x ,Point(i).y-1 ,Point(i+1).x,Point(i+1).y-1 ,RGB(RTL.R,RTL.G,RTL.B))