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From: "Dmitry A. Kazakov" <mailbox@dmitry-kazakov.de>
Newsgroups: comp.lang.ada
Subject: Re: GtkAda callback and event
Date: Fri, 10 Sep 2021 22:58:06 +0200
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On 2021-09-10 22:42, DrPi wrote:

> I didn't think I can extend the widget type to add my own parameters.

Not only for parameters.

Even more frequent purpose is a composite widget. E.g. consider a text 
edit widget with a scroll bar, a menu, some buttons etc. Typically, you 
would take some existing widget and derive your widget from there.

In the Initialize you will create all other widgets and pack them into 
the widget (if it is a container) or Ref them otherwise. In Gtk_New you 
will have custom parameters.

This new widget you could use just as any built-in widget.

Moreover, you can create a new class for your derived widget and add new 
events, properties and styles for external parametrization etc. The 
styles can be set via CSS.

It is a very powerful and versatile mechanism GtkAda offers.

-- 
Regards,
Dmitry A. Kazakov
http://www.dmitry-kazakov.de