Unlike the raw ContextMenuBuilder on the viewer, this also receives
the viewer and the active strings, so you can reuse buildDefaultContextMenu
and add your own items. Return the menu element (the viewer positions and
dismisses it) or null/undefined for no menu.
The
contextMenuBuilderprop of PdfrxProvider / PdfrxViewerApp.Unlike the raw ContextMenuBuilder on the viewer, this also receives the viewer and the active strings, so you can reuse buildDefaultContextMenu and add your own items. Return the menu element (the viewer positions and dismisses it) or
null/undefinedfor no menu.