Will Thompson authored Sep 18, 2018 and Alberto Fanjul committed Mar 13, 2019

If you try to load a non-XML file, such as Glade's own README, the
parser error contains something like this:

    Start tag expected, '<' not found

glade_util_ui_message() treats the supplied message as markup; so the
literal < in the error message trips it up:

    Gtk-WARNING **: Failed to set text 'Error parsing file '/home/wjt/src/gnome/glade/README' on line 1
    Start tag expected, '<' not found
    ' from markup due to error parsing markup: Error on line 2 char 30: Odd character 'f', expected a '=' after attribute name 'not' of element '''

To fix this, escape the message before passing it to
glade_util_ui_message().