store notes area size at render

crates/tek_sequencer/src/sequencer.rs

@@ -103,6 +103,10 @@ pub struct PhraseEditor<E: Engine> {
     pub notes_out: Arc<RwLock<[bool; 128]>>,
     /// Current position of global playhead
     pub now:       Arc<AtomicUsize>,
+    /// Width of notes area at last render
+    pub width:     AtomicUsize,
+    /// Height of notes area at last render
+    pub height:    AtomicUsize,
 }
 /// Phrase player.
 pub struct PhrasePlayer<E: Engine> {
@@ -237,6 +241,8 @@ impl<E: Engine> PhraseEditor<E> {
             entered:   false,
             mode:      false,
             now:       Arc::new(0.into()),
+            width:     0.into(),
+            height:    0.into(),
         }
     }
 }