Move the main handling of disabled up to Widget

There's still a bit to do here, but this migrates the main work up to the
`Widget`. At this point `Button` is pretty much built expressed as a
function of what `Widget` provides in terms of things being disabled.

Focus can still move into disabled controls (or in this case right now, into
a disabled `Button`). The next step is to add something that works alongside
`can_focus` to say if a control is currently capable of receiving focus (in
other words, it's `not disabled and can_focus`).

src/textual/widget.py

@@ -2140,6 +2140,10 @@ class Widget(DOMNode):
         """Update from CSS if has focus state changes."""
         self._update_styles()
 
+    def watch_disabled(self) -> None:
+        # self.can_focus = not self.disabled
+        self._update_styles()
+
     def _size_updated(
         self, size: Size, virtual_size: Size, container_size: Size
     ) -> None:

src/textual/widgets/_button.py

@@ -39,7 +39,7 @@ class Button(Static, can_focus=True):
         text-style: bold;
     }
 
-    Button.-disabled {
+    Button:disabled {
         opacity: 0.4;
         text-opacity: 0.7;
     }
@@ -173,34 +173,30 @@ class Button(Static, can_focus=True):
     def __init__(
         self,
         label: TextType | None = None,
-        disabled: bool = False,
         variant: ButtonVariant = "default",
         *,
         name: str | None = None,
         id: str | None = None,
         classes: str | None = None,
+        disabled: bool = False,
     ):
         """Create a Button widget.
 
         Args:
             label: The text that appears within the button.
-            disabled: Whether the button is disabled or not.
             variant: The variant of the button.
             name: The name of the button.
             id: The ID of the button in the DOM.
             classes: The CSS classes of the button.
+            disabled: Whether the button is disabled or not.
         """
-        super().__init__(name=name, id=id, classes=classes)
+        super().__init__(name=name, id=id, classes=classes, disabled=disabled)
 
         if label is None:
             label = self.css_identifier_styled
 
         self.label = self.validate_label(label)
 
-        self.disabled = disabled
-        if disabled:
-            self.add_class("-disabled")
-
         self.variant = self.validate_variant(variant)
 
     def __rich_repr__(self) -> rich.repr.Result:
@@ -224,9 +220,9 @@ class Button(Static, can_focus=True):
         self.remove_class(f"-{old_variant}")
         self.add_class(f"-{variant}")
 
-    def watch_disabled(self, disabled: bool) -> None:
-        self.set_class(disabled, "-disabled")
-        self.can_focus = not disabled
+    # def watch_disabled(self, disabled: bool) -> None:
+    #     self.set_class(disabled, "-disabled")
+    #     self.can_focus = not disabled
 
     def validate_label(self, label: RenderableType) -> RenderableType:
         """Parse markup for self.label"""
@@ -269,11 +265,11 @@ class Button(Static, can_focus=True):
     def success(
         cls,
         label: TextType | None = None,
-        disabled: bool = False,
         *,
         name: str | None = None,
         id: str | None = None,
         classes: str | None = None,
+        disabled: bool = False,
     ) -> Button:
         """Utility constructor for creating a success Button variant.
 
@@ -289,22 +285,22 @@ class Button(Static, can_focus=True):
         """
         return Button(
             label=label,
-            disabled=disabled,
             variant="success",
             name=name,
             id=id,
             classes=classes,
+            disabled=disabled,
         )
 
     @classmethod
     def warning(
         cls,
         label: TextType | None = None,
-        disabled: bool = False,
         *,
         name: str | None = None,
         id: str | None = None,
         classes: str | None = None,
+        disabled: bool = False,
     ) -> Button:
         """Utility constructor for creating a warning Button variant.
 
@@ -320,22 +316,22 @@ class Button(Static, can_focus=True):
         """
         return Button(
             label=label,
-            disabled=disabled,
             variant="warning",
             name=name,
             id=id,
             classes=classes,
+            disabled=disabled,
         )
 
     @classmethod
     def error(
         cls,
         label: TextType | None = None,
-        disabled: bool = False,
         *,
         name: str | None = None,
         id: str | None = None,
         classes: str | None = None,
+        disabled: bool = False,
     ) -> Button:
         """Utility constructor for creating an error Button variant.
 
@@ -351,9 +347,9 @@ class Button(Static, can_focus=True):
         """
         return Button(
             label=label,
-            disabled=disabled,
             variant="error",
             name=name,
             id=id,
             classes=classes,
+            disabled=disabled,
         )

src/textual/widgets/_static.py

@@ -56,8 +56,9 @@ class Static(Widget, inherit_bindings=False):
         name: str | None = None,
         id: str | None = None,
         classes: str | None = None,
+        disabled: bool = False,
     ) -> None:
-        super().__init__(name=name, id=id, classes=classes)
+        super().__init__(name=name, id=id, classes=classes, disabled=disabled)
         self.expand = expand
         self.shrink = shrink
         self.markup = markup