Finished changes for BarChart and updated CHNAGELOG.

CHANGELOG.md

@@ -19,8 +19,13 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - Termbox is now initialized in 256 color mode by default.
 - Generalized mouse button FSM for use in widgets that need to track mouse
   button clicks.
-- The constructor of the LineChart widget now also returns an error so that it
+
-  can validate its options. This is a breaking change on the LineChart API.
+#### Breaking API changes
+
+- The constructors of all the widgets now also return an error so that they
+  can validate the options. This is a breaking change for the following
+  widgets: BarChart, Gauge, SparkLine, Text. The callers will have to handle
+  the returned error.
 
 ### Fixed
 

termdashdemo/termdashdemo.go

@@ -106,6 +106,11 @@ func layout(ctx context.Context, t terminalapi.Terminal) (*container.Container,
 		),
 	}
 
+	bc, err := newBarChart(ctx)
+	if err != nil {
+		return nil, err
+	}
+
 	don, err := newDonut(ctx)
 	if err != nil {
 		return nil, err
@@ -120,7 +125,7 @@ func layout(ctx context.Context, t terminalapi.Terminal) (*container.Container,
 			container.Top(
 				container.Border(draw.LineStyleLight),
 				container.BorderTitle("BarChart"),
-				container.PlaceWidget(newBarChart(ctx)),
+				container.PlaceWidget(bc),
 				container.BorderTitleAlignRight(),
 			),
 			container.Bottom(