Add managed Window resource and native shell operations

examples/README.md

@@ -2,6 +2,7 @@
 
 | File | Purpose |
 | --- | --- |
+| [window.endor](window.endor) | A managed native Window resizes the actual shell; source callbacks update it and layout follows reported dimensions. |
 | [layout-cache.endor](layout-cache.endor) | Per-occurrence source measurement caches, separate size/paint models, and a band using the logical viewport input. |
 | [source-layout.endor](source-layout.endor) | Source measurement reads its initial Mount parent; source arrangement moves a child and a click updates the shared layout model. |
 | [source-hit.endor](source-hit.endor) | Source circle hit testing, ordinary Block click subscriptions and fallback to the parent through transparent space. |

examples/window.endor

@@ -0,0 +1,26 @@
+class WindowActions {
+    window: Window
+    function compact(self: WindowActions, event: Event): Unit {
+        self.window.resize(900, 600)
+    }
+    function wide(self: WindowActions, event: Event): Unit {
+        self.window.resize(1120, 720)
+    }
+}
+class WindowBand: RectBlock {
+    function measure(self: WindowBand, mount: Mount, constraints: Constraints): MeasureResult {
+        return MeasureResult(constraints.maxWidth, 32)
+    }
+}
+window = ui.window()
+actions = WindowActions(window)
+band = WindowBand(80, 32, 0, "#237A45")
+compact = Button("紧凑窗口 900 × 600")
+wide = Button("宽窗口 1120 × 720")
+compactConnection = compact.on("click", actions.compact)
+wideConnection = wide.on("click", actions.wide)
+page = Page()
+page.render(Column(24, 16, TextBlock("代码与 GUI 操作同一个受管窗口对象"), band, compact, wide))
+page.open(window)
+window.setTitle("Endor Window")
+window.resize(1120, 720)