diff --git a/.github/workflows/test-with-edm-3.8.yml b/.github/workflows/test-with-edm-3.8.yml
new file mode 100644
index 000000000..19c5cfd61
--- /dev/null
+++ b/.github/workflows/test-with-edm-3.8.yml
@@ -0,0 +1,80 @@
+# This workflow targets stable released dependencies from EDM.
+# Note that some packages may not actually be installed from EDM but from
+# PyPI, see ci/edmtool.py implementations.
+
+name: Test with EDM on Python 3.8
+
+on: pull_request
+
+env:
+  INSTALL_EDM_VERSION: 3.5.0
+
+jobs:
+
+  # Test against EDM packages on Linux
+  test-edm-linux-38:
+    strategy:
+      matrix:
+        toolkit: ['null', 'pyside6']
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v2
+      - name: Install Qt dependencies for Linux
+        run: |
+          sudo apt-get update
+          sudo apt-get install libegl1
+          sudo apt-get install libxkbcommon-x11-0
+          sudo apt-get install libglu1-mesa-dev
+          sudo apt-get install libxcb-icccm4
+          sudo apt-get install libxcb-image0
+          sudo apt-get install libxcb-keysyms1
+          sudo apt-get install libxcb-randr0
+          sudo apt-get install libxcb-render-util0
+          sudo apt-get install libxcb-xinerama0
+          sudo apt-get install libxcb-shape0
+          # Needed to work around https://bugreports.qt.io/browse/PYSIDE-1547
+          sudo apt-get install libopengl0
+        if: matrix.toolkit != 'null'
+      - name: Cache EDM packages
+        uses: actions/cache@v2
+        with:
+          path: ~/.cache
+          key: ${{ runner.os }}-3.8-${{ matrix.toolkit }}-${{ hashFiles('ci/edmtool.py') }}
+      - name: Setup EDM
+        uses: enthought/setup-edm-action@v1
+        with:
+          edm-version: ${{ env.INSTALL_EDM_VERSION }}
+      - name: Install click to the default EDM environment
+        run: edm install -y wheel click coverage
+      - name: Install test environment
+        run: edm run -- python ci/edmtool.py install --runtime=3.8 --toolkit=${{ matrix.toolkit }}
+      - name: Flake8
+        run: edm run -- python ci/edmtool.py flake8 --runtime=3.8 --toolkit=${{ matrix.toolkit }}
+        if: matrix.toolkit == 'null'
+      - name: Run tests
+        run: xvfb-run --server-args="-screen 0 1024x768x24" edm run -- python ci/edmtool.py test --runtime=3.8 --toolkit=${{ matrix.toolkit }}
+
+  # Test against EDM packages on Windows and OSX
+  test-with-edm-38:
+    strategy:
+      matrix:
+        os: [macos-latest, windows-latest]
+        toolkit: ['null', 'pyside6']
+    runs-on: ${{ matrix.os }}
+    steps:
+      - uses: actions/checkout@v2
+      - name: Cache EDM packages
+        uses: actions/cache@v2
+        with:
+          path: ~/.cache
+          key: ${{ runner.os }}-3.8-${{ matrix.toolkit }}-${{ hashFiles('ci/edmtool.py') }}
+      - name: Setup EDM
+        uses: enthought/setup-edm-action@v1
+        with:
+          edm-version: ${{ env.INSTALL_EDM_VERSION }}
+      - name: Install click to the default EDM environment
+        run: edm install -y wheel click coverage
+      - name: Install test environment
+        run: edm run -- python ci/edmtool.py install --runtime=3.8 --toolkit=${{ matrix.toolkit }}
+      - name: Run tests
+        run: edm run -- python ci/edmtool.py test --runtime=3.8 --toolkit=${{ matrix.toolkit }}
diff --git a/chaco/plot_containers.py b/chaco/plot_containers.py
index 7ee0046e6..f5eaa4df4 100644
--- a/chaco/plot_containers.py
+++ b/chaco/plot_containers.py
@@ -18,6 +18,7 @@
     array,
     cumsum,
     hstack,
+    resize,
     sum,
     zeros,
     zeros_like,
@@ -182,7 +183,7 @@ class GridPlotContainer(BasePlotContainer):
 
     # The internal component grid, in row-major order.  This gets updated
     # when any of the following traits change: shape, components, grid_components
-    _grid = Array
+    _grid = Array()
 
     _cached_total_size = Any
     _h_size_prefs = Any
@@ -510,7 +511,7 @@ def _reflow_layout(self):
             numrows, numcols = divmod(len(self.components), self.shape[0])
             self.shape = (numrows, numcols)
         grid = array(self.components, dtype=object)
-        grid.resize(self.shape)
+        grid = resize(grid, self.shape)
         grid[grid == 0] = None
         self._grid = grid
         self._layout_needed = True
diff --git a/ci/edmtool.py b/ci/edmtool.py
index 118ec605a..dbd8ddb1f 100644
--- a/ci/edmtool.py
+++ b/ci/edmtool.py
@@ -77,7 +77,8 @@
 import click
 
 supported_combinations = {
-    '3.6': {'pyside2', 'pyqt', 'pyqt5', 'null'},
+    '3.6': {'pyside2', 'pyqt5', 'null'},
+    '3.8': {'pyside6', 'null'},
 }
 
 dependencies = {
@@ -95,7 +96,7 @@
     "swig",
 }
 
-pypi_dependencies = {"sphinx-copybutton"}
+pypi_dependencies = {}
 
 # Dependencies we install from source for cron tests
 # Order from packages with the most dependencies to one with the least
@@ -111,6 +112,7 @@
 
 extra_dependencies = {
     'pyside2': {'pyside2'},
+    'pyside6': {'pyside6'},
     'pyqt': {'pyqt'},
     'pyqt5': {'pyqt5'},
     'null': set()
@@ -118,7 +120,8 @@
 
 doc_dependencies = {
     "sphinx",
-    "enthought_sphinx_theme"
+    "enthought_sphinx_theme",
+    "sphinx-copybutton",
 }
 
 doc_ignore = {
@@ -161,6 +164,7 @@
 
 environment_vars = {
     'pyside2': {'ETS_TOOLKIT': 'qt4', 'QT_API': 'pyside2'},
+    'pyside6': {'ETS_TOOLKIT': 'qt4', 'QT_API': 'pyside6'},
     'pyqt': {'ETS_TOOLKIT': 'qt4', 'QT_API': 'pyqt'},
     'pyqt5': {'ETS_TOOLKIT': 'qt4', 'QT_API': 'pyqt5'},
     'null': {'ETS_TOOLKIT': 'null.image'},
@@ -204,7 +208,7 @@ def install(runtime, toolkit, environment, editable, source):
         | ci_dependencies
     )
 
-    if toolkit == "pyside2":
+    if toolkit.startswith("pyside"):
         addn_repositories = "--add-repository enthought/lgpl"
     else:
         addn_repositories = ""
diff --git a/pyproject.toml b/pyproject.toml
index b1256a319..26b1ea674 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -1,5 +1,5 @@
 [build-system]
-requires = ["cython", "oldest-supported-numpy", "setuptools", "wheel"]
+requires = ["cython", "oldest-supported-numpy", "setuptools<65.2", "wheel"]
 build-backend = "setuptools.build_meta"
 
 [tool.cibuildwheel]