diff --git a/docs/demo_web.js b/docs/demo_web.js
index cbee3b9c..acef4227 100644
--- a/docs/demo_web.js
+++ b/docs/demo_web.js
@@ -212,28 +212,28 @@ function makeMutClosure(arg0, arg1, dtor, f) {
 
     return real;
 }
-function __wbg_adapter_24(arg0, arg1) {
-    wasm._dyn_core__ops__function__FnMut_____Output___R_as_wasm_bindgen__closure__WasmClosure___describe__invoke__hf394391f07d20fc8(arg0, arg1);
+function __wbg_adapter_24(arg0, arg1, arg2) {
+    wasm._dyn_core__ops__function__FnMut__A____Output___R_as_wasm_bindgen__closure__WasmClosure___describe__invoke__h1fcacf2ad60d2387(arg0, arg1, addHeapObject(arg2));
 }
 
-function __wbg_adapter_27(arg0, arg1) {
-    wasm._dyn_core__ops__function__FnMut_____Output___R_as_wasm_bindgen__closure__WasmClosure___describe__invoke__h74e3475b1fcd9cd1(arg0, arg1);
+function __wbg_adapter_27(arg0, arg1, arg2) {
+    wasm._dyn_core__ops__function__FnMut__A____Output___R_as_wasm_bindgen__closure__WasmClosure___describe__invoke__h1fcacf2ad60d2387(arg0, arg1, addHeapObject(arg2));
 }
 
-function __wbg_adapter_30(arg0, arg1, arg2) {
-    wasm._dyn_core__ops__function__FnMut__A____Output___R_as_wasm_bindgen__closure__WasmClosure___describe__invoke__h8ac16b787f5fa676(arg0, arg1, addHeapObject(arg2));
+function __wbg_adapter_30(arg0, arg1) {
+    wasm._dyn_core__ops__function__FnMut_____Output___R_as_wasm_bindgen__closure__WasmClosure___describe__invoke__h2c9bae79cd8d7906(arg0, arg1);
 }
 
-function __wbg_adapter_33(arg0, arg1, arg2) {
-    wasm._dyn_core__ops__function__FnMut__A____Output___R_as_wasm_bindgen__closure__WasmClosure___describe__invoke__h8ac16b787f5fa676(arg0, arg1, addHeapObject(arg2));
+function __wbg_adapter_33(arg0, arg1) {
+    wasm._dyn_core__ops__function__FnMut_____Output___R_as_wasm_bindgen__closure__WasmClosure___describe__invoke__h76852efce6b7a83f(arg0, arg1);
 }
 
 function __wbg_adapter_36(arg0, arg1, arg2) {
-    wasm._dyn_core__ops__function__FnMut__A____Output___R_as_wasm_bindgen__closure__WasmClosure___describe__invoke__h8ac16b787f5fa676(arg0, arg1, addHeapObject(arg2));
+    wasm._dyn_core__ops__function__FnMut__A____Output___R_as_wasm_bindgen__closure__WasmClosure___describe__invoke__h1fcacf2ad60d2387(arg0, arg1, addHeapObject(arg2));
 }
 
 function __wbg_adapter_39(arg0, arg1, arg2) {
-    wasm._dyn_core__ops__function__FnMut__A____Output___R_as_wasm_bindgen__closure__WasmClosure___describe__invoke__h8ac16b787f5fa676(arg0, arg1, addHeapObject(arg2));
+    wasm._dyn_core__ops__function__FnMut__A____Output___R_as_wasm_bindgen__closure__WasmClosure___describe__invoke__h1fcacf2ad60d2387(arg0, arg1, addHeapObject(arg2));
 }
 
 /**
@@ -727,30 +727,30 @@ async function init(input) {
         var ret = wasm.memory;
         return addHeapObject(ret);
     };
-    imports.wbg.__wbindgen_closure_wrapper366 = function(arg0, arg1, arg2) {
-        var ret = makeMutClosure(arg0, arg1, 72, __wbg_adapter_27);
-        return addHeapObject(ret);
-    };
-    imports.wbg.__wbindgen_closure_wrapper364 = function(arg0, arg1, arg2) {
-        var ret = makeMutClosure(arg0, arg1, 72, __wbg_adapter_39);
-        return addHeapObject(ret);
-    };
-    imports.wbg.__wbindgen_closure_wrapper368 = function(arg0, arg1, arg2) {
-        var ret = makeMutClosure(arg0, arg1, 72, __wbg_adapter_33);
-        return addHeapObject(ret);
-    };
-    imports.wbg.__wbindgen_closure_wrapper361 = function(arg0, arg1, arg2) {
-        var ret = makeMutClosure(arg0, arg1, 72, __wbg_adapter_24);
-        return addHeapObject(ret);
-    };
-    imports.wbg.__wbindgen_closure_wrapper370 = function(arg0, arg1, arg2) {
+    imports.wbg.__wbindgen_closure_wrapper360 = function(arg0, arg1, arg2) {
         var ret = makeMutClosure(arg0, arg1, 72, __wbg_adapter_30);
         return addHeapObject(ret);
     };
-    imports.wbg.__wbindgen_closure_wrapper362 = function(arg0, arg1, arg2) {
+    imports.wbg.__wbindgen_closure_wrapper364 = function(arg0, arg1, arg2) {
         var ret = makeMutClosure(arg0, arg1, 72, __wbg_adapter_36);
         return addHeapObject(ret);
     };
+    imports.wbg.__wbindgen_closure_wrapper366 = function(arg0, arg1, arg2) {
+        var ret = makeMutClosure(arg0, arg1, 72, __wbg_adapter_33);
+        return addHeapObject(ret);
+    };
+    imports.wbg.__wbindgen_closure_wrapper368 = function(arg0, arg1, arg2) {
+        var ret = makeMutClosure(arg0, arg1, 72, __wbg_adapter_39);
+        return addHeapObject(ret);
+    };
+    imports.wbg.__wbindgen_closure_wrapper370 = function(arg0, arg1, arg2) {
+        var ret = makeMutClosure(arg0, arg1, 72, __wbg_adapter_24);
+        return addHeapObject(ret);
+    };
+    imports.wbg.__wbindgen_closure_wrapper362 = function(arg0, arg1, arg2) {
+        var ret = makeMutClosure(arg0, arg1, 72, __wbg_adapter_27);
+        return addHeapObject(ret);
+    };
 
     if (typeof input === 'string' || (typeof Request === 'function' && input instanceof Request) || (typeof URL === 'function' && input instanceof URL)) {
         input = fetch(input);
diff --git a/docs/demo_web_bg.wasm b/docs/demo_web_bg.wasm
index b7149c22..82ebff31 100644
Binary files a/docs/demo_web_bg.wasm and b/docs/demo_web_bg.wasm differ
diff --git a/egui/src/demos.rs b/egui/src/demos.rs
index a21f7347..c2edd630 100644
--- a/egui/src/demos.rs
+++ b/egui/src/demos.rs
@@ -3,6 +3,7 @@
 //! The demo-code is also used in benchmarks and tests.
 mod app;
 mod fractal_clock;
+pub mod toggle_switch;
 
 pub use {
     app::{DemoApp, DemoWindow},
diff --git a/egui/src/demos/app.rs b/egui/src/demos/app.rs
index 639b982d..d1d5aafd 100644
--- a/egui/src/demos/app.rs
+++ b/egui/src/demos/app.rs
@@ -397,6 +397,8 @@ impl DemoWindow {
         CollapsingHeader::new("Misc")
             .default_open(false)
             .show(ui, |ui| {
+                super::toggle_switch::demo(ui, &mut self.widgets.button_enabled);
+
                 ui.horizontal(|ui| {
                     ui.label("You can pretty easily paint your own small icons:");
                     let painter = ui.canvas(Vec2::splat(16.0));
diff --git a/egui/src/demos/toggle_switch.rs b/egui/src/demos/toggle_switch.rs
new file mode 100644
index 00000000..106ee1a8
--- /dev/null
+++ b/egui/src/demos/toggle_switch.rs
@@ -0,0 +1,65 @@
+//! Source code example of how to create your own widget.
+use crate::{paint::PaintCmd, *};
+
+// iOS style toggle switch
+pub fn toggle(ui: &mut Ui, on: &mut bool) -> Response {
+    // First we must reserve some space to use:
+    let desired_size = vec2(2.0, 1.0) * ui.style().clickable_diameter;
+    let rect = ui.allocate_space(desired_size);
+
+    // Now that we have an area, we want to check for clicks.
+    // To do that we need an `Id` for the button.
+    // Id's are best created from unique identifiers (like fixed labels)
+    // but since we have no label for the switch we here just generate an `Id` automatically
+    // (based on a rolling counter in the `Ui`).
+    let id = ui.make_position_id();
+    let response = ui.interact(rect, id, Sense::click());
+    if response.clicked {
+        *on = !*on;
+    }
+
+    // For painting, let's ask for a simple animation from Egui.
+    // Egui keeps track of changes in the boolean associated with the id and
+    // returns an animated value between `[0, 1]` for how far along "toggled" we are.
+    let how_on = ui.ctx().animate_bool(id, *on);
+
+    // After interaction (to avoid frame delay), we paint the widget.
+    // We can follow the standard style theme by asking
+    // "how should something that is being interacted with be painted?".
+    // This gives us visual style change when the user hovers and clicks on the widget.
+    let style = ui.style().interact(&response);
+    let off_color = Rgba::new(0.0, 0.0, 0.0, 0.0);
+    let on_color = Rgba::new(0.0, 0.5, 0.0, 0.5);
+    // All coordinates are in screen coordinates (not relative)
+    // so we use `rect` to place the elements.
+    let radius = 0.5 * rect.height();
+    ui.painter().add(PaintCmd::Rect {
+        rect,
+        corner_radius: radius,
+        outline: style.bg_outline,
+        fill: Some(lerp(off_color..=on_color, how_on).into()),
+    });
+    // Animate the circle from left to right:
+    let circle_x = lerp((rect.left() + radius)..=(rect.right() - radius), how_on);
+    ui.painter().add(PaintCmd::Circle {
+        center: pos2(circle_x, rect.center().y),
+        radius: 0.75 * radius,
+        outline: Some(style.line_style()),
+        fill: Some(style.main_fill),
+    });
+
+    // All done! Return the response so the user can check what happened
+    // (hoovered, clicked, ...) and show a tooltip.
+
+    response
+}
+
+pub fn demo(ui: &mut Ui, on: &mut bool) {
+    ui.label("Example of how to create your own widget from scratch.");
+    let url = format!("https://github.com/emilk/egui/blob/master/{}", file!());
+    ui.horizontal_centered(|ui| {
+        ui.label("My beautiful toggle switch:");
+        toggle(ui, on).tooltip_text("Click to toggle");
+        ui.add(Hyperlink::new(url).text("(source code)"));
+    });
+}