T16 review fixes: an unknown system zone stops instead of reading as UTC, the view window refits when data shrinks, the volume profile counts narrow and flat candles whole, Fibonacci labels stay in their pane, the DOM ladder shows its tick's decimals, the tape flashes on each new trade, typed numbers reach their owner before a press, and a smaller loss than expected reads as a beat

src/finance/renko.rs

@@ -17,7 +17,10 @@ use crate::{
         ChartTooltip, Linear, Rect, Tiles, anchored, at, finish, measure, place, ring, tracked,
     },
     theme::{ActiveTheme, TextSize},
-    typography::{format, tabular},
+    typography::{
+        format::{self, system_zone},
+        tabular,
+    },
 };
 
 /// A mark on a price-only chart: its slot, the prices it spans, whether it rose, and its words.
@@ -221,7 +224,7 @@ pub struct RenkoChart {
     id: ElementId,
     candles: Rc<Vec<Candle>>,
     size: f64,
-    zone: TimeZone,
+    zone: Option<TimeZone>,
     red_up: bool,
 }
 
@@ -236,7 +239,7 @@ impl RenkoChart {
             id: id.into(),
             candles: candles.into(),
             size,
-            zone: TimeZone::system(),
+            zone: None,
             red_up: false,
         }
     }
@@ -248,7 +251,7 @@ impl RenkoChart {
 
     /// The time zone its dates read in; the system's unless set.
     pub fn zone(mut self, zone: TimeZone) -> Self {
-        self.zone = zone;
+        self.zone = Some(zone);
         self
     }
 }
@@ -261,13 +264,17 @@ impl Styled for RenkoChart {
 
 impl RenderOnce for RenkoChart {
     fn render(mut self, window: &mut Window, cx: &mut App) -> impl IntoElement {
+        let zone = self
+            .zone
+            .clone()
+            .unwrap_or_else(|| system_zone("RenkoChart"));
         let marks = renko(&self.candles, self.size)
             .into_iter()
             .enumerate()
             .map(|(slot, brick)| {
                 let day = self.candles[brick.at]
                     .time
-                    .to_zoned(self.zone.clone())
+                    .to_zoned(zone.clone())
                     .strftime("%b %-d, %Y")
                     .to_string();
                 let reading = format!(