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...enable/disable the system menu close button at run-time?
Autor: Pavel Marek
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Tip Rating (3):  
     


(*
--- english -------------------------------------------------------------------
This is a component, so you are free to install it but must not: you can also
dynamically create an instance of it at runtime.
--- german --------------------------------------------------------------------
Es handelt sich hier um eine Komponente. Sie können es wie gewonnt installieren
oder einfach eine Instanz von der Objektklasse erst zur Laufzeit erzeugen.
*)



unit UNoCloseForm;

interface

uses
  
Windows, Messages, SysUtils, Classes, Graphics, Controls, Forms, Dialogs;

type
  
TNoCloseForm = class(TComponent)
  private
    
{ Private declarations }
    
FCloseEnabled: boolean;
    procedure SetCloseEnabled (Value: boolean);
  protected
    
{ Protected declarations }
  
public
    
{ Public declarations }
    
constructor Create (AOwner: TComponent); override;
    destructor Destroy; override;
    procedure Toggle;
  published
    
{ Published declarations }
    
property CloseEnabled: boolean read FCloseEnabled write SetCloseEnabled default False;
  end;

procedure Register;

implementation

type 
THackWinControl = class (TWinControl);

constructor TNoCloseForm.Create (AOwner: TComponent);
begin
 inherited 
Create (AOwner);
 FCloseEnabled := False;
 Toggle;
end;

destructor TNoCloseForm.Destroy;
begin
 if 
(csDesigning in ComponentState) then
  
CloseEnabled:=True;
 inherited Destroy;
end;

procedure TNoCloseForm.SetCloseEnabled (Value: boolean);
begin
 if 
Value<>FCloseEnabled then
  try
  
Toggle;
  FCloseEnabled := Value;
  except end;
end;

procedure TNoCloseForm.Toggle;
var WCTRL: THackWinControl; LI: LongInt;
begin
  if not 
Assigned(Owner) or (csDesigning in ComponentState) then Exit;
  WCTRL := THackWinControl (Owner);
  LI := GetClassLong(WCTRL.Handle, GCL_STYLE);
  LI := LI xor CS_NOCLOSE;
  SetClassLong(WCTRL.Handle, GCL_STYLE, LI);
  WCTRL.RecreateWnd;
end;

procedure Register;
begin
  
RegisterComponents('Samples', [TNoCloseForm]);
end;

end.



 

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