fix: mark reponse changed when knob was dragged

examples/example_knob.rs

@@ -23,11 +23,14 @@ impl eframe::App for KnobExample {
     fn update(&mut self, ctx: &egui::Context, _frame: &mut eframe::Frame) {
         egui::CentralPanel::default().show(ctx, |ui| {
             ui.horizontal(|ui| {
-                ui.add(
+                if ui.add(
                     Knob::new(&mut self.value, 0.0, 100.0, egui_knob::KnobStyle::Dot)
                         .with_label("Gain", egui_knob::LabelPosition::Bottom)
                         .with_size(50.0),
-                );
+                ).changed(){
+                    println!("Value changed");
+                }
+
                 ui.add(
                     Knob::new(&mut self.value, 0.0, 100.0, egui_knob::KnobStyle::Wiper)
                         .with_label("Gain", egui_knob::LabelPosition::Bottom)

src/lib.rs

@@ -104,13 +104,14 @@ impl Widget for Knob<'_> {
             knob_size.y + label_size.y + label_padding * 6.0,
         );
 
-        let (rect, response) = ui.allocate_exact_size(adjusted_size, Sense::drag());
+        let (rect, mut response) = ui.allocate_exact_size(adjusted_size, Sense::drag());
 
         if response.dragged() {
             let delta = response.drag_delta().y;
             let range = self.max - self.min;
             let step = range * 0.005;
             *self.value = (*self.value - delta * step).clamp(self.min, self.max);
+            response.mark_changed();
         }
 
         let painter = ui.painter();