[gthumb] curve editor grid: use antialiasing for the diagonal

[Paolo Bacchilega <paobac src gnome org>]

commit 78c7b2f55dbc54928b7fcf155ffcb2b0d2b8f028
Author: Paolo Bacchilega <paobac src gnome org>
Date:   Sun Jan 18 18:54:55 2015 +0100

    curve editor grid: use antialiasing for the diagonal

 extensions/file_tools/gth-curve-editor.c |    2 ++
 1 files changed, 2 insertions(+), 0 deletions(-)
---
diff --git a/extensions/file_tools/gth-curve-editor.c b/extensions/file_tools/gth-curve-editor.c
index a8a7d06..eef3b5a 100644
--- a/extensions/file_tools/gth-curve-editor.c
+++ b/extensions/file_tools/gth-curve-editor.c
@@ -315,6 +315,8 @@ gth_histogram_paint_grid (GthCurveEditor  *self,
        }
 
        /* diagonal */
+
+       cairo_set_antialias (cr, CAIRO_ANTIALIAS_DEFAULT);
        cairo_set_line_width (cr, 1.0);
        cairo_set_source_rgba (cr, color.red, color.green, color.blue, 0.5);
        cairo_move_to (cr, allocation->x + 0.5, allocation->y + allocation->height + 0.5);