constants LayoutChangingEnum
Generally, the control fires the LayoutStartChanging / LayoutEndChanging event when an UI operation is performed. The Operation parameter of the LayoutStartChanging / LayoutEndChanging events support the values as listed:

NameValueDescription
exLayoutResizePanels0 One of the panels has been resized. The PaneWidth property indicates the width of the left/right panel.
exCalendarSelectionChange1 Specifies whether the selection in the calendar panel is changing/changed. The Selection property of the Calendar returns a safe array of selected dates. The /NET or /WPF version provides the SelDates property of List<DateTime> type to get or sets the new selection using a collection of DateTime objects. The LayoutStartChanging(exCalendarSelectionChange) specifies that the user is about to change the selection in the calendar panel, while the LayoutEndChanging( exCalendarSelectionChange) specifies whether the user changed the selection in the calendar panel.
exCalendarFocusDateChange2 Specifies whether the focused date in the calendar panel is changing/changed. The FocusDate property indicates the date being focused in the calendar.  The LayoutStartChanging(exCalendarFocusDateChange) specifies that a new date is about to be focused on the calendar panel, while the LayoutEndChanging( exCalendarFocusDateChange) specifies whether a new date has been focused.
exCalendarDateChange3 Specifies whether the browsing date in the calendar panel is changing/changed. The Date property of the Calendar object indicates the month date being browsed in the calendar. The LayoutStartChanging(exCalendarDateChange) specifies that a new month is about to be shown on the calendar panel, while the LayoutEndChanging( exCalendarDateChange) specifies whether the new month has been browsed. The FirstVisibleDate/LastVisibleDate property indicates the first visible date in the calendar panel.
exScheduleMove4 Specifies whether the control is automatically scrolled by drag and drop. By default, you can press the SHIFT + Click and drag the schedule view to a new position. The AllowMoveSchedule property allows the user to move or navigate the schedule view to a new position, without selecting a new date in the calendar panel. 
exScheduleResize5 The user is zooming the dates in the control. By default, you can click the middle mouse button, and drag the cursor to a new position, so the schedule view gets zoomed or resized. The AllowResizeSchedule property indicates the keys combination so the user can resize the schedule view at runtime.
exScheduleResizeTimeScale6 The user is resizing the time scale. The TimeScales property access the control's TimeScale objects. The Width property of the time scale indicates the width in pixels of the time scale. The AllowResizeTimeScale property indicates the keys the user can resize at runtime the time scale. 
exLayoutCalendarAutoHide7 The calendar is auto shown or hidden. The OnResizeControl property on exCalendarAutoHide makes the calendar goes away if the cursor is not in it. The PaneWidth property indicates the width of the left/right panel. For instance, the PaneWidth(False) on 0, indicates that the calendar panel is hidden, or if it not zero, the calendar panel is shown. You can call the FitSelToView method during this operation so the schedule fits the selected dates in its client area.
exScheduleCreateEvent8 The user crates a new event by dragging the mouse. The AddEvent event notifies your application once a new event is added to the schedule view.
exScheduleResizeGroup9 The user resizes a group. The user can resize a group by clicking the groups header between two groups, and start dragging the cursor to a new position, and so the group is being resized. The AllowResizeGroup property specifies whether the user can resize a group at runtime.
exScheduleSelectionChange10 Specifies whether the selection in the schedule panel is changing/changed. You can use the AllowSelectEvent property to change the key to allow the user select new events or you can prevent selecting any event using exDisallow value. The Selectable property of the event indicates whether the event can be selected at runtime. The Selection property gets or sets a safe array of selected events. The /NET or /WPF version provides the SelEvents property of List<Event> type to get or sets the new selection using a collection of Event objects.
exScheduleMoveEvent11 Indicates whether the user moves the event. The control fires the UpdateEvent event once the margin of the events are being updated.
exScheduleResizeStartEvent12 Indicates whether the user resizes the start of the event. The control fires the UpdateEvent event once the margin of the events are being updated. 
exScheduleResizeEndEvent13 Indicates whether the user resizes the end of the event. The control fires the UpdateEvent event once the margin of the events are being updated.
exScheduleMoveMarkTime14 Indicates whether the user is about to move a MarkTime object. The Movable property of the MarkTime object indicates whether the user can move at runtime the MarkTime object using the Mouse. The MarkTimeFromPoint(-1,-1) property indicates the MarkTime object from the cursor. You can use the MarkTimeFromPoint(-1,-1) method during the LayoutStartChanging( exScheduleMoveMarkTime) to store the timer from the cursor to a global member, and when LayoutEndChanging( exScheduleMoveMarkTime) occurs, you can use the previously stored member to identify the timer being moved/updated at runtime.
exScheduleEditEvent15 The user edit the event's caption. The event notifies once the user starts inline editing an appointment. The Editable property of the Event indicates the property of the Event to be edited at runtime. You can use the EventFromPoint(-1,-1) method during the LayoutStartChanging( exScheduleEditEvent) to store the event from the cursor to a global member, and when LayoutEndChanging( exScheduleEditEvent) occurs, you can use the previously stored member to identify the event being edited.
exLayoutExchangePanels16 The panels of the control has been exchanged. The AllowExchangePanels property indicates the combination of keys that user can use so it can drag a panel from a position to another. The control provides two panels, the calendar panel and the schedule panel. By default, the calendar panel is displayed on the left side, while the schedule view is displayed on the right side. The OnResizeControl property specifies when the calendar/schedule view is displayed on left/right side of the control.
exScheduleScrollAllDayEvent17 The user scrolls the all-day events. The AllowAllDayEventScroll property gets or sets a value that specifies whether the all-day event header supports scrolling.
exScheduleMoveGroup18 The user moves a group. The AllowMoveGroup property specifies whether the user can move a group at runtime.
exUndo33 An Undo operation is performed. The AllowUndoRedo property enables or disables the control's Undo/Redo feature.
exRedo34 A Redo operation is performed. The AllowUndoRedo property enables or disables the control's Undo/Redo feature.
exUndoRedoUpdate32 The Undo/Redo queue is updated. The AllowUndoRedo property enables or disables the control's Undo/Redo feature.