If radio is TRUE, the cell renderer renders a radio toggle
(i.e. a toggle in a group of mutually-exclusive toggles).
If FALSE, it renders a check toggle (a standalone boolean option).
This can be set globally for the cell renderer, or changed just
before rendering each cell in the model (for gtk.TreeView, you set
up a per-row setting using gtk.TreeViewColumn to associate model
columns with cell renderer properties).
If radio is TRUE, the cell renderer renders a radio toggle (i.e. a toggle in a group of mutually-exclusive toggles). If FALSE, it renders a check toggle (a standalone boolean option). This can be set globally for the cell renderer, or changed just before rendering each cell in the model (for gtk.TreeView, you set up a per-row setting using gtk.TreeViewColumn to associate model columns with cell renderer properties).