docs: Add page for ProgressExtensions

doc/helpers/progress-extensions.md

@@ -0,0 +1,34 @@
+---
+uid: Toolkit.Helpers.ProgressExtensions
+---
+
+# Progress Extensions
+
+Provides attached properties to easily change the behavior of progress controls (ie. `ProgressBar` and `ProgressRing`), when nested in a complex visual tree.
+
+## Remarks
+
+This attached property is useful to indicate that some operation is ongoing for an entire section of a view, without having to manually set the `IsActive` property of each nested progress control.
+
+## Attached Properties
+
+| Property            | Type        | Description                                                                                   |
+|---------------------|-------------|-----------------------------------------------------------------------------------------------|
+| `IsActive`          | `bool`      | Once applied to a `FrameworkElement`, this property value sets whether its visual descendant progress controls display a loading indicator. |
+
+Setting `ProgressExtensions.IsActive` to `true` will recursively enable the loading animation on all `ProgressBar` and `ProgressRing` controls in the visual tree.
+
+## Usage
+
+```xml
+<!-- Include the following XAML namespace to use the samples below -->
+xmlns:utu="using:Uno.Toolkit.UI"
+...
+
+<Grid>
+    <ContentPresenter 
+        x:Name="WeeklyPromotionsPresenter"
+        Content="{TemplateBinding WeeklyPromotionsContent}"
+        utu:ProgressExtensions.IsActive="True"
+...
+```

doc/toc.yml

@@ -61,6 +61,8 @@
       href: helpers/input-extensions.md
     - name: ItemsRepeater Extensions
       href: helpers/itemsrepeater-extensions.md
+    - name: Progress Extensions
+      href: helpers/progress-extensions.md
     - name: Responsive markup extension
       href: helpers/responsive-extension.md
     - name: StatusBar attached properties