lablgtk 2.18.12

Error log

The package failed to build. The error log from opam follows.

Opam plugin "depext" may require upgrading/reinstalling. Reinstall the plugin on the current switch? [Y/n] y
The following actions will be performed:
  - recompile opam-depext 1.2.3

<><> Processing actions <><><><><><><><><><><><><><><><><><><><><><><><><><><><>
-> retrieved opam-depext.1.2.3  (cached)
-> removed   opam-depext.1.2.3
-> installed opam-depext.1.2.3
Done.

<><> opam-depext.1.2.3 installed successfully <><><><><><><><><><><><><><><><><>
=> opam-depext is unnecessary when used with opam >= 2.1. Please use opam install directly instead
# Run eval $(opam env) to update the current shell environment

<><> Carrying on to "opam depext -viy ocaml-top.1.1.5 seq.base re.1.9.0 ocp-pp.1.99.19-beta ocp-index.1.3.6 ocp-indent.1.8.1 ocamlfind.1.9.6 lablgtk.2.18.12 jbuilder.transition dune.1.11.4 cppo.1.6.9 conf-pkg-config.3 conf-gtksourceview.2 conf-gtk2.1 cmdliner.1.3.0 base-bytes.base" 

Since version 2.1, opam now handles external dependencies alongside OCaml ones, and the `depext` plugin interface is provided for backwards compatibility only. Consider using your usual `opam install` command to install both OCaml and system dependencies, or `opam install <pkg> --depext-only` if you want to only install external dependencies.
# Detecting depexts using vars: arch=x86_64, os=linux, os-distribution=debian, os-family=debian
[ERROR] No solution for ocaml-top.1.1.5 & seq.base & re.1.9.0 & ocp-pp.1.99.19-beta & ocp-index.1.3.6 & ocp-indent.1.8.1 & ocamlfind.1.9.6 & lablgtk.2.18.12 & jbuilder.transition & dune.1.11.4 & cppo.1.6.9 & conf-pkg-config.3 & conf-gtksourceview.2 & conf-gtk2.1 & cmdliner.1.3.0 & base-bytes.base:   * Missing dependency:
            - conf-gtksourceview
            depends on the unavailable system package 'libgtksourceview2.0-dev'. Use `--no-depexts' to attempt installation anyway, or it is possible that a depext package name in the opam file is incorrect.


Command failed: opam --cli=2.1 list --readonly --external '--resolve=ocaml-top.1.1.5,seq.base,re.1.9.0,ocp-pp.1.99.19-beta,ocp-index.1.3.6,ocp-indent.1.8.1,ocamlfind.1.9.6,lablgtk.2.18.12,jbuilder.transition,dune.1.11.4,cppo.1.6.9,conf-pkg-config.3,conf-gtksourceview.2,conf-gtk2.1,cmdliner.1.3.0,base-bytes.base' --color=never returned 20