Set the value of the theme_name property.
This will cause the icon theme to be loaded if it differs from the existing theme name. If the theme could not be loaded, it will fall back to using the default icon theme (hicolor).
This will override the system's theme setting. To revert to the system icon theme, this function can be called with a null
theme_name argument.
| this | |
| theme_name |
the name of an icon theme to load, or |