Pointer to the current plug-in instance.
The browser calls NPP_HandleEvent to tell the plug-in when events take place in the plug-in's window or drawable area. The plug-in either handles or ignores the event, depending on the value given in the event parameter of this function. For a list of event types the application is responsible for delivering to the plug-in, see the NPEvent structure.
The browser gives each windowed plug-in its own native window, often a child window of the browser window, to draw into. The plug-in has complete control over drawing and event handling within that window. §
The browser does not give a windowed plug-in a native window, because the Mac OS platform does not support child windows. Instead, the windowed plug-in draws into the graphics port associated with the the browser window, at the offset that the browser specifies. For this reason, NPP_HandleEvent is only way the plug-in can receive events from its host application on Mac OS. When NPP_HandleEvent is called, the current port is set up so that its origin matches the top-left corner of the plug-in. A plug-in does not need to set up the current port for mouse coordinate translation. §