The following is a list of possible values for these events:
LVI_WND_ATTR - Window Bidi attributes changed.
LVI_WND_STAT - Window Bidi status changed.
LVI_FOCUS_CHANGED - The focus window has changed.
LVI_KBD_LAYER - The system keyboard layer has changed.
LVI_ALL - All information in the viewer must be updated.
LVI_HIDE - This value is used when the system notifies the
viewer to hide itself (such as when another viewer
is the active one).