Keep the focus in a GtkEntry

[Jean-Louis Schmitt <jls jls-info com>]

Hi

In a Window, I have several GtkEntry, and I have connected to them a callback function through the 
focus_out_event signal.
In this function, I test the validity of the input. If this input is not correct, after displaying an error 
message, I want this GtkEntry continue to grab the focus.
I try to do that with the gtk_widget_grab_focus function, but this method doesn't work. I suppose this 
function will be Ok only if called outside of the concerned widget connected functions.
Can somebody confirm?
How can I do to achieve this?

Thanks for help

Jean-Louis Schmitt
(France)