WinEvent (TWinEvent component) supports most of MSAA (Microsoft Active Accessibility) possibilities which allow to monitor many system events. With TWinEvent you can track some low-level things which were available with global hooks and external DLLs before.
MSAA allows to track many system event, like foregound window switching, move/resize window, minimize/restore window, mouse capturing/releasing, menu start/end, changing selection in tree view, list view, list box, etc., window and control scrolling, changing value in edit boxes and many more... See the full list of TWinEvent's events:
OnWinEvent, OnSystemAlert, OnForegroundWindow, OnMenuStart, OnMenuEnd, OnMenuPopupStart, OnMenuPopupEnd, OnCaptureStart, OnCaptureEnd, OnMoveSizeStart, OnMoveSizeEnd, OnContextHelpStart, OnContextHelpEnd, OnScrollingStart, OnScrollingEnd, OnSwitchStart, OnSwitchEnd, OnMinimizeStart, OnMinimizeEnd, OnObjectCreate, OnObjectDestroy, OnObjectShow, OnObjectHide, OnObjectReorder, OnObjectFocus, OnObjectSelection, OnObjectSelectionAdd, OnObjectSelectionRemove, OnObjectSelectionWithin, OnObjectStateChange, OnObjectLocationChange, OnObjectNameChange, OnObjectValueChange