[gui] fix TailLayout margin

src/main/haxework/gui/layout/TailLayout.hx

@@ -36,6 +36,7 @@ class TailLayout extends DefaultLayout {
             (rowSize > 0 && row.views.length >= rowSize) ||
             (rowSize == 0 && row.width + view.width + margin + group.geometry.margin.horizontal > group.width)
             ) {
+                row.width -= margin;
                 w = Math.max(w, row.width);
                 rows.push(row);
                 row = {
@@ -48,6 +49,7 @@ class TailLayout extends DefaultLayout {
             row.width += view.width + margin;
             row.height = Math.max(row.height, view.height);
         }
+        row.width -= margin;
         w = Math.max(w, row.width);
         rows.push(row);
         var h:Float = Lambda.fold(rows, function(row, h) return row.height + h, 0) + margin * (rows.length - 1);