[evince] ev-view: don't show tooltips for empty annotations

[Nelson Benítez León <nbenitez src gnome org>]

commit de9657875d6da3a14ec3ac852079cdcb00d74f6f
Author: Nelson Benítez León <nbenitezl+gnome gmail com>
Date:   Sun Dec 10 17:03:30 2017 +0500

    ev-view: don't show tooltips for empty annotations
    
    Empty annotations can be quite common, eg. when
    adding highlight annotations where the user doesn't
    enter a comment.
    
    So don't show show empty tooltips as they are useless.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=772621

 libview/ev-view.c |    3 ++-
 1 files changed, 2 insertions(+), 1 deletions(-)
---
diff --git a/libview/ev-view.c b/libview/ev-view.c
index bb63b50..5a19a75 100644
--- a/libview/ev-view.c
+++ b/libview/ev-view.c
@@ -4752,7 +4752,8 @@ ev_view_query_tooltip (GtkWidget  *widget,
        if (annot) {
                const gchar *contents;
 
-               if ((contents = ev_annotation_get_contents (annot))) {
+               contents = ev_annotation_get_contents (annot);
+               if (contents && *contents != '\0') {
                        GdkRectangle annot_area;
 
                        get_annot_area (view, x, y, annot, &annot_area);