Constructs an editor reactor object that notifies of an event related to moving or sizing an AutoCAD window

(vlr-window-reactor data callbacks)



Any AutoLISP data to be associated with the reactor object; otherwise nil if no data.


A list of pairs of the following form:

(event-name . callback_function)

where event-name is one of the symbols listed in the “Window reactor events” table below, and callback_function is a symbol representing a function to be called when the event fires. Each callback function accepts two arguments:

reactor_object The VLR object that called the callback function.

list A list of extra data elements associated with the particular event. The contents of this list for particular events are shown in the “Window reactor callback data” table.

Return Values

The reactor_object argument.

Window reactor events

Event name



An MDI child frame window (a document window) has been moved or resized.


The main AutoCAD window has been moved or resized.

Window reactor callback data


List length





The first parameter is an integer containing the HWND of the window.

The second parameter indicates whether the window has been moved or resized. The value is T if the window has been moved, nil if the window has been resized.