new option: igonre_newline

see github issue 83

config.def.h

@@ -22,6 +22,7 @@ float bounce_freq = 1;          /* determines the bounce frequency (if activated
 int sticky_history = True;
 int verbosity = 0;
 int word_wrap = False;
+int ignore_newline = False;
 int line_height = 0;   /* if line height < font height, it will be raised to font height */
 
 int separator_height = 2; /* height of the separator line between two notifications */

dunst.c

@@ -1078,6 +1078,10 @@ int init_notification(notification * n, int id)
         while (strstr(n->msg, "\\n") != NULL)
                 n->msg = string_replace("\\n", "\n", n->msg);
 
+        if (ignore_newline)
+                while (strstr(n->msg, "\n") != NULL)
+                        n->msg = string_replace("\n", " ", n->msg);
+
         n->msg = rstrip(n->msg);
 
 
@@ -1613,6 +1617,10 @@ void load_options(char *cmdline_config_path)
         word_wrap =
             option_get_bool("global", "word_wrap", "-word_wrap", word_wrap,
                             "Truncating long lines or do word wrap");
+
+        ignore_newline =
+            option_get_bool("global", "ignore_newline", "-ignore_newline",
+                            ignore_newline, "Ignore newline characters in notifications");
         idle_threshold =
             option_get_int("global", "idle_threshold", "-idle_threshold",
                            idle_threshold,

dunstrc

@@ -30,9 +30,12 @@
     # set to -1 to disable
     show_age_threshold = 60;
 
-    # split long notifications into multiple lines
+    # split notifications into multiple lines if they don't fit into geometry
     word_wrap = yes
 
+    # ignore newlines '\n' in notifications
+    ignore_newline = no
+
 
     # the geometry of the window
     # geometry [{width}]x{height}][+/-{x}+/-{y}]