resizable: Let an application build its own resize handle

.theme-schema.json

@@ -325,6 +325,10 @@
           "description": "Progress bar background color.",
           "type": ["string", "null"]
         },
+        "resizable.border": {
+          "description": "The hairline a resize handle draws at rest. Falls back to `border`.",
+          "type": ["string", "null"]
+        },
         "ring": {
           "description": "Used for focus ring.",
           "type": ["string", "null"]

crates/base/src/lib.rs

@@ -149,13 +149,13 @@ pub use progress::{Progress, ProgressIndicator, ProgressTrack};
 pub use radio::{Radio, RadioStyles};
 pub use radio_group::RadioGroup;
 pub use reduce_motion::apply_system_reduce_motion;
+#[doc(hidden)]
+pub use resizable::PANEL_MIN_SIZE;
 pub use resizable::{
     HandleEdge, ResizablePanel, ResizablePanelEvent, ResizablePanelGroup, ResizableState,
-    ResizeHandleContext, ResizeHandleRenderer, ResizeHandleState, h_resizable, resizable_panel,
-    v_resizable,
+    ResizeHandle, ResizeHandleContext, ResizeHandleRenderer, ResizeHandleState, h_resizable,
+    resizable_panel, resize_handle, v_resizable,
 };
-#[doc(hidden)]
-pub use resizable::{PANEL_MIN_SIZE, resize_handle};
 pub use root::{Root, RootPlugin};
 pub use scroll_bounce::{ScrollBounce, ScrollBounceMotion};
 pub use scrollable_mask::ScrollableMask;

crates/base/src/resizable/mod.rs

@@ -7,8 +7,10 @@ use gpui::{
 mod panel;
 mod resize_handle;
 pub use panel::*;
-#[doc(hidden)]
-pub use resize_handle::*;
+pub use resize_handle::{
+    HandleEdge, ResizeHandle, ResizeHandleContext, ResizeHandleRenderer, ResizeHandleState,
+    resize_handle,
+};
 
 #[doc(hidden)]
 pub const PANEL_MIN_SIZE: Pixels = px(100.);

crates/base/src/resizable/panel.rs

@@ -1,13 +1,10 @@
-use std::{
-    ops::{Deref, Range},
-    rc::Rc,
-};
+use std::{ops::Range, rc::Rc};
 
 use gpui::{
     Along, AnyElement, App, AppContext, Axis, Bounds, Context, Element, ElementId, Empty, Entity,
     EventEmitter, InteractiveElement as _, IntoElement, IsZero as _, MouseMoveEvent, MouseUpEvent,
-    ParentElement, Pixels, Render, RenderOnce, Style, StyleRefinement, Styled, Window, div,
-    prelude::FluentBuilder,
+    ParentElement, Pixels, Render, RenderOnce, StatefulInteractiveElement as _, Style,
+    StyleRefinement, Styled, Window, div, prelude::FluentBuilder,
 };
 
 use crate::{AxisExt, ElementExt, StyledExt as _, h_flex, resizable::PANEL_MIN_SIZE, v_flex};
@@ -373,7 +370,7 @@ impl RenderOnce for ResizablePanel {
                             state.update(cx, |state, _| {
                                 state.resizing_panel_ix = Some(ix);
                             });
-                            cx.new(|_| drag_panel.deref().clone())
+                            cx.new(|_| drag_panel.clone())
                         }),
                 )
             })