Convert Unix path separators on Windows when opening documents

Unix path separators can occur e.g. when using MSYS.
Windows does not allow filenames to contain Unix path separators so
this should be safe.

src/utils.c

@@ -1903,6 +1903,10 @@ void utils_tidy_path(gchar *filename)
 	if (str->len >= 2 && strncmp(str->str, "\\\\", 2) == 0)
 		preserve_double_backslash = TRUE;
 
+#ifdef G_OS_WIN32
+	/* using MSYS we can get Unix-style separators */
+	utils_string_replace_all(str, "/", G_DIR_SEPARATOR_S);
+#endif
 	/* replace "/./" and "//" */
 	utils_string_replace_all(str, G_DIR_SEPARATOR_S "." G_DIR_SEPARATOR_S, G_DIR_SEPARATOR_S);
 	utils_string_replace_all(str, G_DIR_SEPARATOR_S G_DIR_SEPARATOR_S, G_DIR_SEPARATOR_S);