[webkit-gtk] window.webkit undefined?

[Antonio]

Hi all,

First of all: apologies if this is not an appropriate mailing list for 
questions about the webkit-gtk API. In this case, would you please point 
me to a proper one?

The fact is that I'm trying to receive messages from a <script> in my 
webpage through the "window.webkit.messageHandlers.XYZ.postMessage()" 
call, as indicated in [1], but "window.webkit" is undefined.

How so? Has this changed somehow?

Thanks in advance,
Antonio

[1]
https://webkitgtk.org/reference/webkit2gtk/2.38.3/signal.UserContentManager.script-message-received.html

NOTE: I've already

a) set up a signal callback to "script-message-received::XYZ"
b) and registered a message handler with 
webkit_user_content_manager_register_script_message_handler(userContentManager, 
"XYZ")