diff --git a/CHANGELOG.md b/CHANGELOG.md
index 741844755..5ce4a8c70 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -25,6 +25,10 @@ Please only add new entries below the [Unreleased](#unreleased---releasedate) he
 
 ## [@Unreleased] - @ReleaseDate
 
+### Breaking
+
+- **core**: `GenWidget::gen_widget` no longer requires a `&mut BuildCtx` parameter. (#pr @M-Adoo)
+
 ## [0.4.0-alpha.5] - 2024-08-14
 
 ### Features
diff --git a/core/src/builtin_widgets/theme.rs b/core/src/builtin_widgets/theme.rs
index dc50d2ea8..adf15c652 100644
--- a/core/src/builtin_widgets/theme.rs
+++ b/core/src/builtin_widgets/theme.rs
@@ -73,9 +73,7 @@ pub struct ThemeWidget {
 
 impl ComposeChild<'static> for ThemeWidget {
   type Child = GenWidget;
-  fn compose_child(
-    this: impl StateWriter<Value = Self>, mut child: Self::Child,
-  ) -> Widget<'static> {
+  fn compose_child(this: impl StateWriter<Value = Self>, child: Self::Child) -> Widget<'static> {
     use crate::prelude::*;
     let f = move |ctx: &BuildCtx| {
       let theme = this.read().theme.clone();
@@ -95,7 +93,7 @@ impl ComposeChild<'static> for ThemeWidget {
 
       // shadow the context with the theme.
       let ctx = BuildCtx::new_with_data(Some(p), ctx.tree, themes);
-      let child = child.gen_widget(&ctx).build(&ctx);
+      let child = child.gen_widget().build(&ctx);
       p.append(child, &mut ctx.tree.borrow_mut());
 
       p
diff --git a/core/src/overlay.rs b/core/src/overlay.rs
index d4cb1fce7..fa943941b 100644
--- a/core/src/overlay.rs
+++ b/core/src/overlay.rs
@@ -33,7 +33,7 @@ impl OverlayCloseHandle {
   pub fn close(&self) { self.0.close() }
 }
 
-type Builder = Box<dyn FnMut(OverlayCloseHandle, &BuildCtx) -> Widget<'static>>;
+type Builder = Box<dyn FnMut(OverlayCloseHandle) -> Widget<'static>>;
 struct OverlayData {
   builder: Builder,
   style: Option<OverlayStyle>,
@@ -67,8 +67,8 @@ impl Overlay {
   ///  App::run(w);
   /// ```
   pub fn new(gen: impl Into<GenWidget>) -> Self {
-    let mut gen = gen.into();
-    Self::inner_new(Box::new(move |_, ctx| gen.gen_widget(ctx)))
+    let gen = gen.into();
+    Self::inner_new(Box::new(move |_| gen.gen_widget()))
   }
 
   /// Create overlay from a builder with a close_handle
@@ -100,9 +100,9 @@ impl Overlay {
   /// App::run(w).with_size(Size::new(200., 200.));
   /// ```
   pub fn new_with_handle(
-    mut builder: impl FnMut(OverlayCloseHandle) -> Widget<'static> + 'static,
+    builder: impl FnMut(OverlayCloseHandle) -> Widget<'static> + 'static,
   ) -> Self {
-    Self::inner_new(Box::new(move |ctrl, _| builder(ctrl)))
+    Self::inner_new(Box::new(builder))
   }
 
   /// Overlay will show with the given style, if the overlay have not been set
@@ -115,10 +115,10 @@ impl Overlay {
     if self.is_show() {
       return;
     }
-    let ctx = BuildCtx::new(None, &wnd.widget_tree);
+
     let mut inner = self.0.borrow_mut();
     let handle = inner.state.close_handle();
-    let w = (inner.builder)(handle, &ctx);
+    let w = (inner.builder)(handle);
     let style = inner.style.clone();
     inner.state.show(w, style, wnd);
   }
@@ -168,10 +168,9 @@ impl Overlay {
       return;
     }
 
-    let ctx = BuildCtx::new(None, &wnd.widget_tree);
     let mut inner = self.0.borrow_mut();
     let close_handle = inner.state.close_handle();
-    let overlay = (inner.builder)(close_handle.clone(), &ctx);
+    let overlay = (inner.builder)(close_handle.clone());
     let overlay = f(overlay, close_handle);
     let style = inner.style.clone();
     inner
diff --git a/core/src/widget.rs b/core/src/widget.rs
index 35ea6c567..c27b3539a 100644
--- a/core/src/widget.rs
+++ b/core/src/widget.rs
@@ -1,3 +1,4 @@
+use std::cell::RefCell;
 #[doc(hidden)]
 pub use std::{
   any::{Any, TypeId},
@@ -5,6 +6,7 @@ pub use std::{
   ops::Deref,
 };
 
+use ribir_algo::Sc;
 use widget_id::{new_node, RenderQueryable};
 
 pub(crate) use crate::widget_tree::*;
@@ -82,7 +84,8 @@ impl<'w> LazyWidget<'w> {
 
 /// A boxed function widget that can be called multiple times to regenerate
 /// widget.
-pub struct GenWidget(Box<dyn FnMut(&BuildCtx) -> Widget<'static>>);
+pub struct GenWidget(InnerGenWidget);
+type InnerGenWidget = Sc<RefCell<Box<dyn FnMut(&BuildCtx) -> Widget<'static>>>>;
 
 // The widget type marker.
 pub const COMPOSE: usize = 1;
@@ -147,7 +150,7 @@ where
 
 impl IntoWidgetStrict<'static, FN> for GenWidget {
   #[inline]
-  fn into_widget_strict(self) -> Widget<'static> { self.0.into_widget_strict() }
+  fn into_widget_strict(self) -> Widget<'static> { self.gen_widget() }
 }
 
 impl<'a> Widget<'a> {
@@ -180,10 +183,15 @@ impl<'a> Widget<'a> {
 }
 impl GenWidget {
   #[inline]
-  pub fn new(f: impl FnMut(&BuildCtx) -> Widget<'static> + 'static) -> Self { Self(Box::new(f)) }
+  pub fn new(f: impl FnMut(&BuildCtx) -> Widget<'static> + 'static) -> Self {
+    Self(Sc::new(RefCell::new(Box::new(f))))
+  }
 
   #[inline]
-  pub fn gen_widget(&mut self, ctx: &BuildCtx) -> Widget<'static> { (self.0)(ctx) }
+  pub fn gen_widget(&self) -> Widget<'static> {
+    let f = self.0.clone();
+    fn_widget! { f.borrow_mut()(ctx!()) }.into_widget()
+  }
 }
 
 impl<F: FnMut(&BuildCtx) -> Widget<'static> + 'static> From<F> for GenWidget {
diff --git a/macros/src/lib.rs b/macros/src/lib.rs
index 31c490f5d..f3355d730 100644
--- a/macros/src/lib.rs
+++ b/macros/src/lib.rs
@@ -72,7 +72,8 @@ pub fn lerp_derive(input: TokenStream) -> TokenStream {
 ///   `declare!` to build the `XXX` widget.
 /// - for every field of `XXXBuilder`
 ///   - implement method with same name of the field and use to init the field.
-///  [declare]: ../ribir/declare/index.html
+///
+/// [declare]: ../ribir/declare/index.html
 #[proc_macro_derive(Declare, attributes(declare))]
 pub fn declare_trait_macro_derive(input: TokenStream) -> TokenStream {
   let mut input = parse_macro_input!(input as DeriveInput);
diff --git a/widgets/src/tabs.rs b/widgets/src/tabs.rs
index af488ceb8..586449d39 100644
--- a/widgets/src/tabs.rs
+++ b/widgets/src/tabs.rs
@@ -319,7 +319,7 @@ impl ComposeChild<'static> for Tabs {
           },
           @ { header }
           @Expanded {
-            @ { pipe!($this.cur_idx).map(move |idx| panes[idx].gen_widget(ctx!())) }
+            @ { pipe!($this.cur_idx).map(move |idx| panes[idx].gen_widget()) }
           }
         }
       }