How is it possiple to move an control over the form ?

It's very simple - so don't try to write hundreds of lines to solve this problem

just take a look at this small source-snip

all what we need to do is to override the dynamic MouseDown method of the TControl-BaseClass and fire an WM_SysCommand event with the magicKey $F012.

best regards

Boris Benjamin Wittfoth



{-----------------------------------------------------------------------------


hEaDRoOm Development
29.10.2002

Unit Name: HREdit
Author:    Benjamin Benjamin Wittfoth
Purpose:
History:
-----------------------------------------------------------------------------}
unit HREdit;

interface

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

type
  THREdit = class(TEdit)
  private
    fDragable:Boolean;
  protected
    procedure MouseDown(Button: TMouseButton;Shift: TShiftState; X, Y: Integer);override;
  public
    Constructor Create(AOwner:TComponent);override;
    Destructor Destroy;override;
  published
    property Dragable:Boolean read fDragable write fDragable;
  end;

procedure Register;

implementation

procedure Register;
begin
  RegisterComponents('HEADROOM DEVELOPMENT', [THREdit]);
end;

{ THREdit }
constructor THREdit.Create(AOwner: TComponent);
begin
  inherited Create(AOwner);
end;

destructor THREdit.Destroy;
begin
  inherited;
end;

procedure THREdit.MouseDown(Button: TMouseButton; Shift: TShiftState; X,
  Y: Integer);
const
  SC_DragMove = $F012; // important key  !!
begin
  inherited;
  if assigned(onMouseDown)then
    OnMouseDown(self,Button,Shift,x,y);
  if fDragable then
  begin
    ReleaseCapture;
    (self as TControl).perform(WM_SysCommand, SC_DragMove, 0); // this is the key !
  end;
end;

end.