`NSDocument`'s `data(ofType:)` getting data from (async) `actor`

When using resources such as brushes, templates and styles in WPF, they can be specified either as StaticResources

<Rectangle Fill="{StaticResource MyBrush}" />

or as a DynamicResource

<ItemsControl ItemTemplate="{DynamicResource MyItemTemplate}"  />

Most of the times (always?), only one works and the other will throw exception during runtime. But I'd like to know why:

What is the main difference. Like memory or performance implications
Are there rules in WPF like "brushes are always static" and "templates are always dynamic" etc.?

I assume the choice between Static vs Dynamic isn't as arbitrary as it seems... but I fail to see the pattern.

A StaticResource will be resolved and assigned to the property during the loading of the XAML which occurs before the application is actually run. It will only be assigned once and any changes to resource dictionary ignored.

A DynamicResource assigns an Expression object to the property during loading but does not actually lookup the resource until runtime when the Expression object is asked for the value. This defers looking up the resource until it is needed at runtime. A good example would be a forward reference to a resource defined later on in the XAML. Another example is a resource that will not even exist until runtime. It will update the target if the source resource dictionary is changed.

I was also confused about them. See this example below:

<Window x:Class="WpfApplicationWPF.CommandsWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        Title="CommandsWindow" Height="300" Width="300">

    <StackPanel>
        <Button Name="ButtonNew" 
                Click="ButtonNew_Click" 
                Background="{DynamicResource PinkBrush}">NEW</Button>
        <Image Name="ImageNew" 
               Source="pack://application:,,,/images/winter.jpg"></Image>
    </StackPanel>


    <Window.Background>
        <DynamicResource ResourceKey="PinkBrush"></DynamicResource>
    </Window.Background>

</Window>

Here I have used dynamic resource for button and window and have not declared it anywhere.Upon runtime, the ResourceDictionary of the hierarchy will be checked.Since I have not defined it, I guess the default will be used.

If I add the code below to click event of Button, since they use DynamicResource, the background will be updated accordingly.

private void ButtonNew_Click(object sender, RoutedEventArgs e)
{
    this.Resources.Add(  "PinkBrush"
                         ,new SolidColorBrush(SystemColors.DesktopColor)
                       );
}

If they had used StaticResource:

The resource has to be declared in XAML
And that too "before" they are used.

Hope I cleared some confusion.

StaticResource will be resolved on object construction.
DynamicResource will be evaluated and resolved every time control needs the resource.

`NSDocument`'s `data(ofType:)` getting data from (async) `actor`

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