wip: p.52, e=5, collecting tui by layer p.2

crates/tek_tui/src/tui_focus.rs

@@ -213,3 +213,31 @@ impl FocusGrid for ArrangerTui {
         }
     }
 }
+
+/// Focused field of `PhraseLength`
+#[derive(Copy, Clone)]
+pub enum PhraseLengthFocus {
+    /// Editing the number of bars
+    Bar,
+    /// Editing the number of beats
+    Beat,
+    /// Editing the number of ticks
+    Tick,
+}
+
+impl PhraseLengthFocus {
+    pub fn next (&mut self) {
+        *self = match self {
+            Self::Bar  => Self::Beat,
+            Self::Beat => Self::Tick,
+            Self::Tick => Self::Bar,
+        }
+    }
+    pub fn prev (&mut self) {
+        *self = match self {
+            Self::Bar  => Self::Tick,
+            Self::Beat => Self::Bar,
+            Self::Tick => Self::Beat,
+        }
+    }
+}