The &xwp; PM hook is a routine in XWPDAEMN.EXE which can, if enabled, monitor and manipulate Presentation Manager (PM) messages.

This allows &xwp; to manipulate the behavior of all windows and keyboard and mouse events on your system. This is how object hotkeys, sliding focus, sliding menus, screen border objects, &pgr; etc. work. If a certain event is detected by the hook, &xwp; can take a special action, such as opening an object or making another window active.

As a consequence, the &xwp; PM hook must be enabled first for all those features to work.

The problem with PM hooks is that they are global. Since several applications can install such hooks, they might conflict. Well-known OS/2 tools that install hooks also are NPS WPS, WarpEnhancer, DragText, and others. This is why &xwp; allows you disable its PM hook altogether, in case it is conflicting with some other application.