[Pkg-pascal-devel] Bug#967284: Bug#967284: GTK 2 -> 3 in Castle Game Engine

[Abou Al Montacir]

Hi Michalis,

On Mon, 2026-02-09 at 03:03 +0000, Michalis Kamburelis wrote:
...
> In Castle Game Engine, GTK 2 is used in 2 ways:
> 
> 1. As a backend of our TCastleWindow. This was solved on our
> (upstream) side -- we introduced now a new backend
> CASTLE_WINDOW_GTK_3 and it's now default on Linux and FreeBSD. So all
> applications using TCastleWindow can be compiled to use GTK 2 instead
> of 3.
> 
>   More information on
> https://castle-engine.io/wp/2026/02/09/upgrade-to-gtk-3/ .
> 
>   So this should be solved once we (upstream) release new engine
> version (we plan to do it this month, February 2026) and Debian
> updates to it.
Now we have fp-units-gtk3 on debian, so maybe you can use them?
> 
> 2. Another usage is through using LCL, this affects our editor
> (castle-editor) application. The editor doesn't use TCastleWindow, it
> uses Lazarus LCL + TCastleControl component. There are a few
> solutions to this usage:
> 
> 2.1. In short, for Debian packaging, as a simplest solution we
> recommend to use LCL Qt5 widgetset for castle-editor.
> 
>   We did some fixes around TCastleControl + Qt5 widgetset in the
> past, and it should work nicely.
> 
>   Note that this is *not* what we will do as an upstream, in our
> releases on https://castle-engine.io/download . Using Qt5 widgetset
> would be risky for us, as it has to rely on libqt5pas, which changes
> API from time to time, and distributing a binary castle-editor that
> links to incompatible libqtpas would just crash on users. This will
> change once we use Snap / Flatpak for Linux releases (then we can
> package engine + proper libqtpas) but for current releases it would
> be bad. Anyhow, this problem doesn't concern Debian, where you can
> just make sure that libqt5pas and castle-editor are compatible, since
> you ship them both.
> 
> 2.2. We could rely on Lazarus GTK 3 widgetset.
> 
>   It is unfortunately still not stable enough for us. Even testing
> with latest Lazarus "main", where "gtk3" is no longer marked "alpha".
> I mentioned details on
> https://castle-engine.io/wp/2026/02/09/upgrade-to-gtk-3/ .
> 
>   I want to work on this, and once done -> this can be a solution for
> both upstream and Debian packaging. But it may not be immediate.
Maybe with new version of Lazarus you can do this easier. Please note
that Lazarus itself is not really usable with GTK3 WS, but many
applications will run just fine.

According to some upstream tickets, we may expect Lazarus 5.0 by end of
year.
> 
> 2.3. There is also, but this is a more distant future, possibility to
> have castle-editor version that doesn't use LCL, and only uses
> TCastleWindow. So then our engine editor is also a "more typical"
> application using our engine. I actually started to play with this
> idea in the past, it's called castle-editor-portable,
> https://github.com/castle-engine/castle-engine/tree/master/tools/castle-editor-portable
>  . But this needs a lot of work to be really "production" usage at
> this point.
-- 
Cheers,
Abou Al Montacir
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