CellRendererCombo renders text in a cell like CellRendererText from which it is derived.
But while CellRendererText offers a simple entry to edit the text, CellRendererCombo offers a ComboBox widget to edit the text. The values to display in the combo box are taken from the tree model specified in the model property.
The combo cell renderer takes care of adding a text cell renderer to the combo box and sets it to display the column specified by its text_column property. Further properties of the combo box can be set in a handler for the editing_started signal.
The CellRendererCombo cell renderer was added in GTK+ 2.6.