[gtkmm] Gtk::CellRendererText: and validations

[Leandro Fanzone <leandro hasar com>]

I am trying to derive a custom class from Gtk::CellRendererText to 
achieve basic validations. I fail to understand how this can be done. I 
override on_edited(), but such function only has a readonly string with 
the new text as a parameter (besides the path), so I can't modify it in 
case it's an invalid string. I can't also use property_text() to change 
the cell, it won't have any effect. I tried to follow the source code, 
but I didn't understand how to do this. To call edited() from on_edited 
is to recurse infinitely. To call the parent's virtual function also 
won't work. Any ideas?
Thank you very much,

Leandro Fanzone.