✨ Add an illustration for Textualize/textual#3517

loading_test.py

@@ -0,0 +1,38 @@
+"""https://github.com/Textualize/textual/issues/3517"""
+
+from textual.app import App, ComposeResult
+from textual.containers import Grid, Container
+
+class BusyBox(Container, can_focus=True):
+
+    DEFAULT_CSS = """
+    BusyBox {
+        border: panel red;
+    }
+    BusyBox:focus {
+        border: panel green;
+    }
+    """
+
+    def __init__(self, number: int) -> None:
+        super().__init__()
+        self.border_title = f"Busy box {number}"
+        self.loading = bool(number % 3)
+
+class LoadingApp(App[None]):
+
+    CSS = """
+    Grid {
+        grid-size: 4;
+    }
+    """
+
+    def compose(self) -> ComposeResult:
+        with Grid():
+            for n in range(16):
+                yield BusyBox(n)
+
+if __name__ == "__main__":
+    LoadingApp().run()
+
+### loading_test.py ends here