要到 WPF 在执行阶段将物件树状结构执行个体化时，才会呼叫型别转换子。

Type converters are not called until the object tree is instantiated by WPF at runtime.

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此外，如果视觉化树状结构的变更强制更新复合场景图形，也会呼叫事件处理常式方法。

In addition, if changes to the visual tree force updates to the composition scene graph, your event handler method is also called.

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如果在呼叫项目上找不到资源，则会改以搜寻逻辑树状结构内的父项目，接著搜寻应用程式、布景主题，最后则会搜寻系统资源。

If the resource is not found on the calling element, the parent element in the logical tree is searched next, then the application, then themes, and finally system resources.

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