Missing docstring & restore snapshot

crates/egui/src/widget_style.rs

@@ -218,13 +218,18 @@ impl Style {
     }
 }
 
-/// The root class is present on every top-level ui
+/// The root class is a special class present on every top-level [`Ui`].
 pub const ROOT_CLASS: &str = "root";
+/// The selected class is a special class present on selected [`Button`].
 pub const SELECTED_CLASS: &str = "selected";
 
+/// A class is a static string identifier.
 pub type ClassName = Cow<'static, str>;
 
-/// The classes assigned to a widget
+/// Classes are string identifier that can be set on widget/Ui.
+///
+/// This can be used by styling engine to compute a different style
+/// based on the set of classes present on the widget/Ui.
 #[derive(Debug, Default, Clone)]
 pub struct Classes {
     classes: SmallVec<[ClassName; 5]>,

crates/egui_demo_app/tests/snapshots/clock.png

@@ -1,3 +1,3 @@
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-size 335380
+oid sha256:e4cff85a005ad897624f6c7a2b2ad599325ec99e0b3c9c35963f16611f283997
+size 335371

crates/egui_kittest/tests/snapshots/should_wait_for_images.png

@@ -1,3 +1,3 @@
 version https://git-lfs.github.com/spec/v1
-oid sha256:845acb34152fb829dc24c606b1741e250f1d1fa645236ef57fce0cbda104c465
-size 2121
+oid sha256:ad75a0e568e04c20d0e3b823c7e4906c39dcd0a69a086d8e30714a9e4530d031
+size 2128