`GtkCellRendererSpinner` renders a spinning animation in a cell, very similar to `GtkSpinner`. It can often be used as an alternative to
a `GtkCellRendererProgress` for displaying indefinite activity, instead of actual progress.
To start the animation in a cell, set the `GtkCellRendererSpinner:active` property to true and
increment the `GtkCellRendererSpinner:pulse` property at regular intervals. The usual way to set the cell renderer properties for each
cell is to bind them to columns in your tree model using e.g. gtk_tree_view_column_add_attribute.