refactor events; watch prep work

wlx-overlay-s/src/gui/timer.rs

@@ -0,0 +1,26 @@
+use std::time::{Duration, Instant};
+
+pub struct GuiTimer {
+    interval: Duration,
+    next_tick: Instant,
+    signal: usize,
+}
+
+impl GuiTimer {
+    pub fn new(interval: Duration, signal: usize) -> Self {
+        Self {
+            interval,
+            next_tick: Instant::now() + interval,
+            signal,
+        }
+    }
+
+    pub fn check_tick(&mut self) -> Option<usize> {
+        if self.next_tick > Instant::now() {
+            return None;
+        }
+
+        self.next_tick = Instant::now() + self.interval;
+        Some(self.signal)
+    }
+}