validation.pl - Accepts only ASCII letters.
This sample program shows how to make a simple text validation widget. This particular example considers ASCII letters as being the only valid characters, any other character will be underlined in red but still accepted by the widget.
To install Gtk2::Ex::Entry::Pango, copy and paste the appropriate command in to your terminal.
cpanm
cpanm Gtk2::Ex::Entry::Pango
CPAN shell
perl -MCPAN -e shell install Gtk2::Ex::Entry::Pango
For more information on module installation, please visit the detailed CPAN module installation guide.