Call update on Painter from Container

This would cause painter to not invalidate as expected.

- fixes #988

CHANGELOG.md

@@ -111,6 +111,7 @@ This means that druid no longer requires cairo on macOS and uses Core Graphics i
 - Focus request handling is now predictable with the last request overriding earlier ones. ([#948] by [@xStrom])
 - Wheel events now properly update hot state. ([#951] by [@xStrom])
 - X11: Support mouse scrolling. ([#961] by [@jneem])
+- Painter widget not repainting on data change in Container ([#991] by [@cmyr])
 
 ### Visual
 
@@ -231,6 +232,7 @@ This means that druid no longer requires cairo on macOS and uses Core Graphics i
 [#970]: https://github.com/xi-editor/druid/pull/970
 [#980]: https://github.com/xi-editor/druid/pull/980
 [#982]: https://github.com/xi-editor/druid/pull/982
+[#991]: https://github.com/xi-editor/druid/pull/991
 
 ## [0.5.0] - 2020-04-01
 

druid/src/widget/container.rs

@@ -106,7 +106,10 @@ impl<T: Data> Widget<T> for Container<T> {
         self.inner.lifecycle(ctx, event, data, env)
     }
 
-    fn update(&mut self, ctx: &mut UpdateCtx, _old_data: &T, data: &T, env: &Env) {
+    fn update(&mut self, ctx: &mut UpdateCtx, old_data: &T, data: &T, env: &Env) {
+        if let Some(BackgroundBrush::Painter(p)) = self.background.as_mut() {
+            p.update(ctx, old_data, data, env);
+        }
         self.inner.update(ctx, data, env);
     }