add scrollarea

examples/gallery/src/main.rs

@@ -13,6 +13,7 @@ use gpui_native_core::link::Link;
 use gpui_native_core::popover::Popover;
 use gpui_native_core::progress::Progress;
 use gpui_native_core::radio::{Radio, RadioGroup};
+use gpui_native_core::scroll_area::ScrollArea;
 use gpui_native_core::slider::Slider;
 use gpui_native_core::switch::Switch;
 use gpui_native_core::toggle::Toggle;
@@ -29,6 +30,7 @@ struct Gallery {
     volume: f32,
     input_state: Entity<InputState>,
     popover_open: bool,
+    scroll: gpui::ScrollHandle,
 }
 
 impl Render for Gallery {
@@ -98,8 +100,7 @@ impl Render for Gallery {
             ("destructive", ButtonVariant::Destructive),
         ];
 
-        div()
-            .size_full()
+        let content = div()
             .font_family(".SystemUIFont")
             .bg(colors.background)
             .text_color(colors.foreground)
@@ -582,7 +583,14 @@ impl Render for Gallery {
                                 .map(|role| icon(*role).size(20.0).color(colors.foreground)),
                         ),
                     ),
-            )
+            );
+
+        // The whole gallery scrolls, demonstrating the scroll area at the
+        // page level: the thumb floats over the window's content.
+        ScrollArea::new("gallery-scroll")
+            .handle(self.scroll.clone())
+            .size_full()
+            .child(content)
     }
 }
 
@@ -671,6 +679,7 @@ fn main() {
                     volume: 40.0,
                     input_state,
                     popover_open: false,
+                    scroll: gpui::ScrollHandle::new(),
                 })
             },
         ) {