How to change the icon of a running program

[PWungsten]

I have a self-written program. I followed the instructions [https://forums.linuxmint.com/viewtopic.php?t=398622] to set an icon: Right-click on Menu button > Configure... > Open the menu editor > (select program) > Properties > (change icon there) > OK.

That works on start-up. But, when I click it, then I get another icon for the running process - the default icon (black gear wheel in a white box) .

How do I ensure that the configured icon is used for the running process?

I have created a file ~/.local/share/applications/MyApp.desktop but that does not solve the problem.

Linux Mint 22.3 Cinnamon

[Axel-Erfurt]

You must set a window icon your self-written program. Which programming language did you use?

[PWungsten]

I thought that's what I was doing in the menu editor. How do I set a window icon?

The language is C++.

[Axel-Erfurt]

Gtk3
https://docs.gtk.org/gtk3/method.Window.set_icon.html

Gtk4
https://docs.gtk.org/gtk4/method.Window.set_icon_name.html

gtkmm
https://gnome.pages.gitlab.gnome.org/gtkmm/classGtk_1_1Window.html#a61b485e2dfcfd60a129c258ab1a78820

[PWungsten]

Thanks, none of my web searches revealed that it was done in code. Maybe this should be more widely publicised.

I managed to achieve my objective in QT.