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property OnChanging: TTabChangingEvent read FOnChanging write FOnChanging;


__property TTabChangingEvent OnChanging = {read=FOnChanging, write=FOnChanging};


Type Visibility Source Unit Parent
event protected
Vcl.ComCtrls TCustomTabControl


Occurs immediately before a new tab is selected.

Write an OnChanging event handler to take specific action immediately before the selected tab changes. Set the AllowChange parameter to False to prevent the change.

Use an OnChanging event handler to prevent the user from leaving a tab setting until certain conditions have been met. An OnChanging event handler can also be used to save information about the current state of the tab control before it is changed by a new tab selection.

Note: The event is not called if you change the active page in code, for example, by setting the value of TPageControl.ActivePage.

OnChanging is an event handler of type Vcl.ComCtrls.TTabChangingEvent.

See Also

Code Examples