Convert BigRedButton ctor into just a Bundle

The BigRedButton isn't doing anything that requires the `Commands`, so
it'll be turned back into just a Bundle.

src/widgets/mod.rs

@@ -20,7 +20,11 @@ impl Plugin for GameUiPlugin {
       .add_observer(CloseButton::hover_start)
       .add_observer(CloseButton::hover_stop)
       .add_observer(CloseButton::press_start)
-      .add_observer(CloseButton::press_stop);
+      .add_observer(CloseButton::press_stop)
+      .add_observer(BigRedButton::button_hover_start)
+      .add_observer(BigRedButton::button_hover_stop)
+      .add_observer(BigRedButton::button_press_start)
+      .add_observer(BigRedButton::button_press_stop);
   }
 }
 
@@ -87,10 +91,14 @@ fn machine_ui_base(commands: &mut Commands, header: impl Into<String>, theme: &U
 pub struct BigRedButton;
 
 impl BigRedButton {
-  // TODO: Hook up action handling (callback? Observer? Some other weird component?)
-  fn spawn_big_red_button(commands: &mut ChildSpawnerCommands, text: impl Into<String>) {
-    let mut builder = commands.spawn((
+  /// Default bundle for a Big Red Button. Remember to attach on-press observers!
+  ///
+  /// I haven't figure out what will receive the on-press events, so I'm moving
+  /// the problem. It will not be the button's job to hook up the event notice.
+  fn bundle(text: impl Into<String>) -> impl Bundle {
+    (
       Button,
+      BigRedButton,
       Node {
         width: Px(60.0),
         height: Px(60.0),
@@ -112,11 +120,7 @@ impl BigRedButton {
         TextColor(WHITE.into()),
         TextShadow::default(),
       ],
-    ));
-    builder.observe(BigRedButton::button_hover_start);
-    builder.observe(BigRedButton::button_hover_stop);
-    builder.observe(BigRedButton::button_press_start);
-    builder.observe(BigRedButton::button_press_stop);
+    );
   }
 
   /// Re-color the button when a pointer passes over it
@@ -124,7 +128,7 @@ impl BigRedButton {
     event: Trigger<Pointer<Over>>,
     // Get button background and border colors so we can change them.
     // Filter for *changed* interactions, and only entities with a [`Button`]
-    mut button_colors: Query<(&mut BackgroundColor, &mut BorderColor), With<Button>>,
+    mut button_colors: Query<(&mut BackgroundColor, &mut BorderColor), With<BigRedButton>>,
     ui_theme: Res<UiTheme>,
   ) {
     // Get the components for only the Trigger's target entity
@@ -139,7 +143,7 @@ impl BigRedButton {
 
   fn button_hover_stop(
     event: Trigger<Pointer<Out>>,
-    mut button_colors: Query<(&mut BackgroundColor, &mut BorderColor), With<Button>>,
+    mut button_colors: Query<(&mut BackgroundColor, &mut BorderColor), With<BigRedButton>>,
     ui_theme: Res<UiTheme>,
   ) {
     if let Ok((mut bg, mut border)) = button_colors.get_mut(event.target()) {
@@ -150,7 +154,7 @@ impl BigRedButton {
 
   fn button_press_start(
     event: Trigger<Pointer<Pressed>>,
-    mut button_colors: Query<(&mut BackgroundColor, &mut BorderColor), With<Button>>,
+    mut button_colors: Query<(&mut BackgroundColor, &mut BorderColor), With<BigRedButton>>,
     ui_theme: Res<UiTheme>,
   ) {
     if let Ok((mut bg, mut border)) = button_colors.get_mut(event.target()) {
@@ -161,7 +165,7 @@ impl BigRedButton {
 
   fn button_press_stop(
     event: Trigger<Pointer<Released>>,
-    mut button_colors: Query<(&mut BackgroundColor, &mut BorderColor), With<Button>>,
+    mut button_colors: Query<(&mut BackgroundColor, &mut BorderColor), With<BigRedButton>>,
     ui_theme: Res<UiTheme>,
   ) {
     if let Ok((mut bg, mut border)) = button_colors.get_mut(event.target()) {