A ResizeRequest event reports another client's attempt to change the size of a window. The X server generates this event type when another client calls XConfigureWindow(), XMoveResizeWindow(), or XResizeWindow(). If this event type is selected, the window is not resized. This gives the client that selects this event (usually the window manager) the opportunity to revise the new size of the window before executing the resize request or to deny the request itself.
To receive this event type, specify a window ID and pass ResizeRedirectMask as part of the event_mask argument to XSelectInput. Only one client can select this event on a particular window. When selected, this event is triggered instead of resizing the window.