Use OnCanResize to adjust the way a control is resized. If necessary, change the new width and height of the control in the OnCanResize event handler. The OnCanResize event handler also allows applications to indicate that the entire resize should be aborted. 

If there is no OnCanResize event handler, or if the OnCanResize event handler indicates that the resize attempt can proceed, the OnCanResize event is followed immediately by an OnConstrainedResize event.

TPalettePanel Properties