RegisterHotKey函数原型及说明

BOOL RegisterHotKey(
HWND hWnd, // window to receive hot-key notification
int id, // identifier of hot key
UINT fsModifiers, // key-modifier flags
UINT vk // virtual-key code);
参数 id为你自己定义的一个ID值，对一个线程来讲其值必需在0x0000 - 0xBFFF范围之内，对DLL来讲其值必需在0xC000 - 0xFFFF 范围之内，在同一进程内该值必须唯一
参数 fsModifiers指明与热键联合使用按键，可取值为：MOD_ALT MOD_CONTROL MOD_WIN MOD_SHIFT
参数 vk指明热键的虚拟键码


首先（举个例子）：
RegisterHotKey(handle,globaladdatom('hot key'),MOD_ALT,vk_f12);
然后在form中声明一个函数（过程）：
procedure hotkey(var msg:tmessage);message wm_hotkey;
过程如下：
procedure TForm1.hotkey(var msg:tmessage);
begin
if (msg.LParamHi=VK_F12) and (msg.LParamLo=MOD_ALT) then
begin
form1.show;
SetForegroundWindow(handle);
end;
end;
这样，不管你在什么地方，窗口就会显示出来。
当然，你要GlobalDeleteAtom;

unit Unit1;

interface

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

type
TForm1 = class(TForm)
procedure FormCreate(Sender: TObject);
procedure FormDestroy(Sender: TObject);
private
{ Private declarations }
aatom:atom;
procedure hotkey(var msg:tmessage);message wm_hotkey;
public
{ Public declarations }
end;

var
Form1: TForm1;

implementation

{$R *.DFM}

procedure TForm1.FormCreate(Sender: TObject);
begin
aatom:=globaladdatom('hot key');
RegisterHotKey(handle,aatom,MOD_ALT,vk_f12);
end;

procedure TForm1.hotkey(var msg:tmessage);
begin
if (msg.LParamHi=VK_F12) and (msg.LParamLo=MOD_ALT) then
SetForegroundWindow(handle);
end;

procedure TForm1.FormDestroy(Sender: TObject);
begin
globalDeleteatom(aatom);
end;

end.