Apply the thin line fix for LowDPI displays

Fixes #2298

internal/painter/gl/draw.go

@@ -117,14 +117,18 @@ func (p *glPainter) lineCoords(pos, pos1, pos2 fyne.Position, lineWidth, feather
 	pos2.X = roundToPixel(pos2.X+xPosDiff, p.pixScale)
 	pos2.Y = roundToPixel(pos2.Y+yPosDiff, p.pixScale)
 
-	if lineWidth <= 0.5 && p.pixScale > 1 { // adjust to support 1px drawing on HiDPI (width 0.5)
+	if lineWidth <= 1 {
+		offset := float32(0.5)                  // adjust location for lines < 1pt on regular display
+		if lineWidth <= 0.5 && p.pixScale > 1 { // and for 1px drawing on HiDPI (width 0.5)
+			offset = 0.25
+		}
 		if pos1.X == pos2.X {
-			pos1.X -= 0.25
-			pos2.X -= 0.25
+			pos1.X -= offset
+			pos2.X -= offset
 		}
 		if pos1.Y == pos2.Y {
-			pos1.Y -= 0.25
-			pos2.Y -= 0.25
+			pos1.Y -= offset
+			pos2.Y -= offset
 		}
 	}