TWinControl.CanFocus
From OpenEUO
RO CanFocus : b Indicates whether a control can receive focus.
Use CanFocus to find out if the control can receive input from the user. CanFocus returns true if both the control and its parent(s) have their Visible and Enabled properties set to true. If any of the Visible and Enabled properties of the control or the controls in which it is contained are not true then CanFocus returns false.
