Gets or sets the value associated with the given key.
Assembly: PresentationFramework (in PresentationFramework.dll)
XMLNS for XAML: http://schemas.microsoft.com/winfx/2006/xaml/presentation, http://schemas.microsoft.com/netfx/2007/xaml/presentation
If the requested key is not in this resource dictionary, the framework resource system will also check the merged dictionaries.
Checking a ResourceDictionary by item or index is not generally the preferred way to retrieve resources. You should instead call methods that are capable of participating in the full resource lookup process and look up resources by their keys, and that can find the resources in applications or themes. FindResource is such a method, and is present on any FrameworkElement. Otherwise your attempt to find the resource does not match the true run-time behavior.
However, obtaining resources directly from an individual dictionary might be appropriate if you are retrieving resources from a known ResourceDictionary location, and are doing so to avoid the possible performance and scope implications of run-time key lookup.
You do not use indexers to define collection members in XAML. Instead, you create child elements in markup. The child elements are either child elements of ResourceDictionary, or of a property element where the property type is ResourceDictionary. For details, see the XAML usage sections in ResourceDictionary.