Sets the icon for applications that are launched with this context.
The icon_name will be interpreted in the same way as the Icon field in desktop files. See also [
[email protected]_icon].
If both icon and icon_name are set, the icon_name takes priority. If neither icon or
icon_name is set, the icon is taken from either the file that is passed to launched application or from the `GAppInfo` for
the launched application itself.
| this |
a `GdkAppLaunchContext` |
| icon_name |
an icon name |