Fix writing of custom data nodes (Issue #201)

CHANGES.md

@@ -11,6 +11,7 @@
 - The mxmldoc utility now supports the `SOURCE_DATE_EPOCH` environment
   variable for reproducible builds (Issue #193)
 - The mxmldoc utility now supports Markdown (Issue #194)
+- Fixed writing of custom data values (Issue #201)
 - Added `mxmlNewOpaquef` and `mxmlSetOpaquef` functions to add and set formatted
   opaque string values.
 - The mxmldoc utility scanned and loaded descriptive text differently, causing

mxml-file.c

@@ -2929,7 +2929,7 @@ mxml_write_node(mxml_node_t     *node,	/* I - Node to write */
 	    const char	*newline;	/* Last newline in string */
 
 
-	    if ((data = (*global->custom_save_cb)(node)) == NULL)
+	    if ((data = (*global->custom_save_cb)(current)) == NULL)
 	      return (-1);
 
 	    if (mxml_write_string(data, p, putc_cb) < 0)