An action the user triggered by activating a link or a widget: the viewer performs none of them itself. The shell navigates (GetDestinationViewport(PdfExplicitDestination, PageLayout, in Viewport) for a go-to), asks before opening a URI or another file, and never runs a script (IsScript events are informational).
public sealed class ViewerActionEventArgs : EventArgs
ISO 32000-2 §12.6 (actions, Table 201), §12.6.4.2 (go-to), §12.6.4.3 (remote go-to), §12.6.4.8 (URI), §12.6.4.12 (named actions); spec #33 viewer capability 6.
kind:method, kind:property, kind:ctor. Press Esc to clear.ActionGets the action, one of the activated annotation's action tree in execution order (§12.6.2: Next), or null for a link with a destination (Dest) and no action.AnnotationGets the link or widget activated, or null when the action came from elsewhere.DestinationGets the resolved destination in this document of a go-to (named destinations looked up), or null.IsScriptGets whether the action is a script (a JavaScript action, §12.6.4.17). The viewer never runs scripts: the event only says one was asked for.NamedOperationGets the operation of a named action (§12.6.4.12, Table 216), or null.PageIndexGets the zero-based page a go-to leads to, or null when it leads nowhere in this document.UriGets the absolute URI of a URI action (resolved against the document's base URI), or null.