dash-frontend: clock, wgui: refactoring, non-panicking casts

wgui/src/widget/div.rs

@@ -1,10 +1,16 @@
+use slotmap::Key;
+
+use crate::layout::WidgetID;
+
 use super::{WidgetObj, WidgetState};
 
-pub struct WidgetDiv {}
+pub struct WidgetDiv {
+	id: WidgetID,
+}
 
 impl WidgetDiv {
 	pub fn create() -> WidgetState {
-		WidgetState::new(Box::new(Self {}))
+		WidgetState::new(Box::new(Self { id: WidgetID::null() }))
 	}
 }
 
@@ -12,4 +18,12 @@ impl WidgetObj for WidgetDiv {
 	fn draw(&mut self, _state: &mut super::DrawState, _params: &super::DrawParams) {
 		// no-op
 	}
+
+	fn get_id(&self) -> WidgetID {
+		self.id
+	}
+
+	fn set_id(&mut self, id: WidgetID) {
+		self.id = id;
+	}
 }