Gtk.StyleContext.prototype.add_region

function add_region(region_name:String, flags:Gtk.RegionFlags):void {
    // Gjs wrapper for gtk_style_context_add_region()
}

Adds a region to context, so posterior calls to Gtk.get or any of the gtk_render_*() functions will make use of this new region for styling.

In the CSS file format, a Gtk.TreeView defining a "row" region, would be matched by:

<programlisting> GtkTreeView row { ... } </programlisting>

Pseudo-classes are used for matching flags, so the two following rules: <programlisting> GtkTreeView row:nth-child(even) { ... } GtkTreeView row:nth-child(odd) { ... } </programlisting>

would apply to even and odd rows, respectively.

<note><para>Region names must only contain lowercase letters and '-', starting always with a lowercase letter.</para></note>

Since 3.0