[ASK] Add custom image to menubar using gtkaction

[kapal kardus <kapal kardus gmail com>]

Hello every body,

I'm berginner in gtk,
I have a question, how add custom icon to my menubar using gtkaction?
I have been googling for tow days, but still can't add custom icon to my menubar,
My example code in attachement.

Thank you,, 

Attachment: builder.ui
Description: Binary data

Attachment: main.cpp
Description: Text Data