How to set format in GtkTreeView

1. create

GtkTreeView

with the

GtkTreeViewColumn

and

GtkCellRendererText

as normal;
2. connect the

GtkTreeViewColumn

to the

GtkTreeViewColumn::set_cell_data_func

callback;
3. in the callback, get value from model that you want to format;
4. format the value as you want;
5. set text back via

GtkCellRendererText::set_property('text', $new_value);