Testing GtkSourceView with GTK4 already possible?

My Gentoo Linux does still only provide GTK3.

For testing the GTK4 Nim bindings I generally do:

#
https://discourse.gnome.org/t/installing-gtk4-for-testing-on-opt-ii/3349/4
cd
rm -rf /opt/gtk
rm -rf gtk
git clone https://gitlab.gnome.org/GNOME/gtk.git
cd gtk
meson --prefix /opt/gtk builddir
ninja -C builddir
ninja -C builddir install

Which works fine for basic GTK4. But above command do not provide a recent GtkSourceView. From

/usr/share/gir-1.0/GtkSource-4.gir

I see

  <include name="Gdk" version="3.0"/>
  <include name="Gtk" version="3.0"/>
  <package name="gtksourceview-4"/>

So I assume that I can not test GtkSourceView with GTK4 already, and I assume that trying to install a newer GtkSourceView from gitlab may break my GTK3 system, i.e. gedit?

From

https://blog.gtk.org/2020/07/31/gtk-3-99/

we learn:

For example, if you are using a webkit webview or GtkSourceView or vte, you might find it difficult to try out GTK 4.

So it is better to wait.

Note that install of latest GTK 3.99 for testing with

git clone https://gitlab.gnome.org/GNOME/gtk.git
cd gtk
meson --prefix /opt/gtk builddir
ninja -C builddir
ninja -C builddir install

may give dconf errors (like wrong font size) after

export LD_LIBRARY_PATH=$LD_LIBRARY_PATH:/opt/gtk/lib64/

and launching gtk3 or gtk4 apps.

I was able to fix it with

git clone https://gitlab.gnome.org/GNOME/dconf.git
cd dconf
meson --prefix /opt/gtk builddir
ninja -C builddir
ninja -C builddir install