diff --git a/.editorconfig b/.editorconfig
index fa698fb..5b3c112 100644
--- a/.editorconfig
+++ b/.editorconfig
@@ -13,7 +13,8 @@
 root = true
 
 
-[*]  # For All Files
+[*]
+# Default settings for all files.
 # Unix-style newlines with a newline ending every file
 end_of_line = lf
 insert_final_newline = true
@@ -33,7 +34,8 @@ indent_size = 4
 # 2 space indentation
 indent_size = 2
 
-[*.{json,jsonl,js,jsx,ts,tsx,css,less,scss}]  # Frontend development
+[*.{json,jsonl,js,jsx,ts,tsx,css,less,scss}]
+# Frontend development
 # 2 space indentation
 indent_size = 2
 max_line_length = 80
diff --git a/.github/workflows/meta.yml b/.github/workflows/meta.yml
index b8edec0..6058d80 100644
--- a/.github/workflows/meta.yml
+++ b/.github/workflows/meta.yml
@@ -28,6 +28,9 @@ jobs:
     uses: plone/meta/.github/workflows/qa.yml@main
   test:
     uses: plone/meta/.github/workflows/test.yml@main
+    with:
+
+       py-versions: '["3.10", "3.12"]'
   coverage:
     uses: plone/meta/.github/workflows/coverage.yml@main
   dependencies:
@@ -57,6 +60,13 @@ jobs:
 # os_dependencies = "git libxml2 libxslt"
 ##
 
+##
+# To test against a specific matrix of python versions
+# when running tests jobs, add in .meta.toml:
+# [github]
+# py_versions = "['3.12', '3.11']"
+##
+
 
 ##
 # Specify additional jobs in .meta.toml:
diff --git a/.meta.toml b/.meta.toml
index 87f8b35..5fbb773 100644
--- a/.meta.toml
+++ b/.meta.toml
@@ -3,7 +3,13 @@
 # See the inline comments on how to expand/tweak this configuration file
 [meta]
 template = "default"
-commit-id = "6e36bcc4"
+commit-id = "5d22fbf8"
 
 [pyproject]
 dependencies_ignores = "['plone.formwidget.contenttree']"
+
+[tox]
+constraints_file = "https://dist.plone.org/release/6.1-dev/constraints.txt"
+
+[github]
+py_versions = "[\"3.10\", \"3.12\"]"
diff --git a/dependabot.yml b/dependabot.yml
new file mode 100644
index 0000000..bbd3ab0
--- /dev/null
+++ b/dependabot.yml
@@ -0,0 +1,11 @@
+# Generated from:
+# https://github.com/plone/meta/tree/main/config/default
+# See the inline comments on how to expand/tweak this configuration file
+version: 2
+updates:
+
+  - package-ecosystem: "github-actions"
+    directory: "/"
+    schedule:
+      # Check for updates to GitHub Actions every week
+      interval: "weekly"
diff --git a/news/51.breaking b/news/51.breaking
new file mode 100644
index 0000000..ab4c246
--- /dev/null
+++ b/news/51.breaking
@@ -0,0 +1,2 @@
+Implement new `ContentBrowserWidget` with `pat-contentbrowser` support.
+[petschki]
diff --git a/plone/app/relationfield/behavior.py b/plone/app/relationfield/behavior.py
index d872a91..a8fc2d7 100644
--- a/plone/app/relationfield/behavior.py
+++ b/plone/app/relationfield/behavior.py
@@ -1,4 +1,4 @@
-from plone.app.z3cform.widget import RelatedItemsFieldWidget
+from plone.app.z3cform.widgets.contentbrowser import ContentBrowserFieldWidget
 from plone.autoform import directives as form
 from plone.autoform.interfaces import IFormFieldProvider
 from plone.base import PloneMessageFactory as _
@@ -23,7 +23,7 @@ class IRelatedItems(model.Schema):
     )
     form.widget(
         "relatedItems",
-        RelatedItemsFieldWidget,
+        ContentBrowserFieldWidget,
         vocabulary="plone.app.vocabularies.Catalog",
         pattern_options={
             "recentlyUsed": True  # Just turn on. Config in plone.app.widgets.
diff --git a/pyproject.toml b/pyproject.toml
index 74b71b3..f01853b 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -71,7 +71,7 @@ target-version = ["py38"]
 ##
 
 [tool.codespell]
-ignore-words-list = "discreet,"
+ignore-words-list = "discreet,assertin,"
 skip = "*.po,"
 ##
 # Add extra configuration options in .meta.toml:
@@ -119,6 +119,7 @@ Zope = [
   'Products.CMFCore', 'Products.CMFDynamicViewFTI',
 ]
 python-dateutil = ['dateutil']
+pytest-plone = ['pytest', 'zope.pytestlayer', 'plone.testing', 'plone.app.testing']
 ignore-packages = ['plone.formwidget.contenttree']
 
 ##
@@ -134,13 +135,15 @@ ignore-packages = ['plone.formwidget.contenttree']
 [tool.check-manifest]
 ignore = [
     ".editorconfig",
+    ".flake8",
     ".meta.toml",
     ".pre-commit-config.yaml",
-    "tox.ini",
-    ".flake8",
+    "dependabot.yml",
     "mx.ini",
+    "tox.ini",
 
 ]
+
 ##
 # Add extra configuration options in .meta.toml:
 #  [pyproject]
@@ -148,6 +151,11 @@ ignore = [
 #      "*.map.js",
 #      "*.pyc",
 #  """
+#  check_manifest_extra_lines = """
+#  ignore-bad-ideas = [
+#      "some/test/file/PKG-INFO",
+#  ]
+#  """
 ##
 
 
diff --git a/setup.py b/setup.py
index aadd45f..3759ddb 100644
--- a/setup.py
+++ b/setup.py
@@ -3,7 +3,7 @@
 from setuptools import setup
 
 
-version = "3.0.6.dev0"
+version = "4.0.0.dev0"
 
 long_description = (
     f"{Path('README.rst').read_text()}\n{Path('CHANGES.rst').read_text()}"
@@ -20,7 +20,7 @@
     classifiers=[
         "Development Status :: 5 - Production/Stable",
         "Framework :: Plone",
-        "Framework :: Plone :: 6.0",
+        "Framework :: Plone :: 6.1",
         "Framework :: Plone :: Core",
         "License :: OSI Approved :: GNU General Public License (GPL)",
         "Programming Language :: Python",
@@ -28,6 +28,7 @@
         "Programming Language :: Python :: 3.9",
         "Programming Language :: Python :: 3.10",
         "Programming Language :: Python :: 3.11",
+        "Programming Language :: Python :: 3.12",
         "Topic :: Software Development :: Libraries :: Python Modules",
     ],
     keywords="dexterity relations plone zc.relation",
diff --git a/tox.ini b/tox.ini
index 6c2493c..7a50f19 100644
--- a/tox.ini
+++ b/tox.ini
@@ -108,8 +108,8 @@ set_env =
 ##
 deps =
     zope.testrunner
-    -c https://dist.plone.org/release/6.0-dev/constraints.txt
-    
+    -c https://dist.plone.org/release/6.1-dev/constraints.txt
+
 ##
 # Specify additional deps in .meta.toml:
 #  [tox]
@@ -151,12 +151,13 @@ set_env =
 deps =
     coverage
     zope.testrunner
-    -c https://dist.plone.org/release/6.0-dev/constraints.txt
-    
+    -c https://dist.plone.org/release/6.1-dev/constraints.txt
+
 commands =
     coverage run --branch --source plone.app.relationfield {envbindir}/zope-testrunner --quiet --all --test-path={toxinidir} -s plone.app.relationfield {posargs}
     coverage report -m --format markdown
     coverage xml
+    coverage html
 extras =
     test
 
@@ -168,8 +169,8 @@ deps =
     twine
     build
     towncrier
-    -c https://dist.plone.org/release/6.0-dev/constraints.txt
-    
+    -c https://dist.plone.org/release/6.1-dev/constraints.txt
+
 commands =
     # fake version to not have to install the package
     # we build the change log as news entries might break
@@ -182,6 +183,9 @@ commands =
 description = ensure there are no cyclic dependencies
 use_develop = true
 skip_install = false
+# Here we must always constrain the package deps to what is already installed,
+# otherwise we simply get the latest from PyPI, which may not work.
+constrain_package_deps = true
 set_env =
 
 ##
@@ -196,8 +200,8 @@ allowlist_externals =
 deps =
     pipdeptree
     pipforester
-    -c https://dist.plone.org/release/6.0-dev/constraints.txt
-    
+    -c https://dist.plone.org/release/6.1-dev/constraints.txt
+
 commands =
     # Generate the full dependency tree
     sh -c 'pipdeptree -j > forest.json'