fix: do not share the Expr for text_color and background_color

Signed-off-by: Maarten A. Breddels <[email protected]>

Author: maartenbreddels

ipydatagrid/cellrenderer.py

@@ -68,11 +68,9 @@ class TextRenderer(CellRenderer):
     ).tag(sync=True, **widget_serialization)
     text_color = Union(
         (Color(), Instance(VegaExpr), Instance(ColorScale)),
-        default_value=Expr("default_value"),
     ).tag(sync=True, **widget_serialization)
     background_color = Union(
         (Color(), Instance(VegaExpr), Instance(ColorScale)),
-        default_value=Expr("default_value"),
     ).tag(sync=True, **widget_serialization)
     vertical_alignment = Union(
         (
@@ -98,6 +96,14 @@ class TextRenderer(CellRenderer):
     )
     missing = Unicode("").tag(sync=True)
 
+    @default('text_color')
+    def _default_text_color(self):
+        return Expr("default_value")
+
+    @default('background_color')
+    def _default_background_color(self):
+        return Expr("default_value")
+
 
 class BarRenderer(TextRenderer):
     _model_name = Unicode("BarRendererModel").tag(sync=True)