[gnumeric] GnmStyle: fix boxed type.

[Morten Welinder <mortenw src gnome org>]

commit 4ed548f7330df384dc4b7d7c8a00a2ea1455b8bb
Author: Morten Welinder <terra gnome org>
Date:   Fri Apr 13 12:00:11 2018 -0400

    GnmStyle: fix boxed type.

 src/mstyle.c |   10 ++++++----
 src/mstyle.h |    2 +-
 2 files changed, 7 insertions(+), 5 deletions(-)
---
diff --git a/src/mstyle.c b/src/mstyle.c
index 2eb4bbe..3af5df8 100644
--- a/src/mstyle.c
+++ b/src/mstyle.c
@@ -822,16 +822,18 @@ gnm_style_new_merged (GnmStyle const *base, GnmStyle const *overlay)
  * gnm_style_ref: (skip)
  * @style: #GnmStyle
  *
- * Adds a reference to @style.
+ * Returns: (transfer full): A new reference to @style.
  */
-void
+GnmStyle *
 gnm_style_ref (GnmStyle const *style)
 {
-       g_return_if_fail (style != NULL);
-       g_return_if_fail (style->ref_count > 0);
+       g_return_val_if_fail (style != NULL, NULL);
+       g_return_val_if_fail (style->ref_count > 0, NULL);
 
        ((GnmStyle *)style)->ref_count++;
        d(("ref %p = %d\n", style, style->ref_count));
+
+       return ((GnmStyle *)style);
 }
 
 /**
diff --git a/src/mstyle.h b/src/mstyle.h
index 874ac1d..9001c3a 100644
--- a/src/mstyle.h
+++ b/src/mstyle.h
@@ -68,7 +68,7 @@ GnmStyle   *gnm_style_dup         (GnmStyle const *src);
 void        gnm_style_merge        (GnmStyle *base, GnmStyle const *overlay);
 void        gnm_style_merge_element (GnmStyle *dst, GnmStyle const *src,
                                     GnmStyleElement elem);
-void        gnm_style_ref           (GnmStyle const *style);
+GnmStyle   *gnm_style_ref           (GnmStyle const *style);
 void        gnm_style_unref         (GnmStyle const *style);
 
 GnmStyle   *gnm_style_link_sheet    (GnmStyle *style, Sheet *sheet);