Future-proof Chart against changing Toga Widget initialization

changes/194.misc.rst

@@ -0,0 +1 @@
+The initialization of Chart has been updated to be compatible with Toga 0.5.0.

examples/chart/app.py

@@ -66,16 +66,16 @@ def startup(self):
                 self.chart,
                 toga.Box(
                     children=[toga.Label("𝜇"), self.mu],
-                    style=Pack(padding=(5, 10)),
+                    style=Pack(margin=(5, 10)),
                 ),
                 toga.Box(
                     children=[toga.Label("𝜎"), self.sigma],
-                    style=Pack(padding=(5, 10)),
+                    style=Pack(margin=(5, 10)),
                 ),
                 toga.Button(
                     "Recreate data",
                     on_press=self.recreate_data,
-                    style=Pack(padding=(10, 10, 20, 10)),
+                    style=Pack(margin=(10, 10, 20, 10)),
                 ),
             ],
             style=Pack(direction=COLUMN),

pyproject.toml

@@ -47,6 +47,7 @@ dev = [
     "setuptools_scm == 8.2.0",
     "tox == 4.24.2",
     "toga-dummy >= 0.4.0",
+    "toga-dummy >= 0.5.0, < 0.6.0",
 ]
 # Docs are always built on a specific Python version; see RTD and tox config files.
 docs = [

src/toga_chart/chart.py

@@ -44,6 +44,7 @@ def __init__(
 
         super().__init__(id=id, style=style)
 
+    def _create(self):
         self._impl = self.canvas._impl
 
     @Widget.app.setter