Sets the current header of the row. This is only allowed to be called from a GtkListBoxUpdateHeaderFunc. It will replace any existing header in the row, and be shown in front of the row in the listbox.
the header, or NULL. [allow-none] Since 3.10
See Implementation
Sets the current header of the row. This is only allowed to be called from a GtkListBoxUpdateHeaderFunc. It will replace any existing header in the row, and be shown in front of the row in the listbox.