Adds a palette to the color chooser.
Use [class@Gtk.ColorDialog] instead
If orientation is horizontal, the colors are grouped in rows, with colors_per_line colors in each row. If
horizontal is false, the colors are grouped in columns instead.
The default color palette of [class@Gtk.ColorChooserWidget] has 45 colors, organized in columns of 5 colors (this includes some grays).
The layout of the color chooser widget works best when the palettes have 9-10 columns.
Calling this function for the first time has the side effect of removing the default color palette from the color chooser.
If colors is null, removes all previously added palettes.
| this |
a `GtkColorChooser` |
| orientation |
gtk_orientation_horizontal if the palette should be displayed in rows, gtk_orientation_vertical for columns |
| colors_per_line |
the number of colors to show in each row/column |
| colors |
the colors of the palette |
| n_colors |
the total number of elements in |