Problem with Keyboard hook proc - delphi

Question

The background: My form has a TWebBrowser. I want to close the form with ESC but the TWebBrowser eats the keystrokes - so I decided to go with a keyboard hook.
The problem is that the Form can be open in multiple instances at the same time.
No matter what I do, in some situations, if there are two instances open of my form, closing one of them closes the other as well.
I've attached some sample code. Any ideas on what causes the issue?
var
EmailDetailsForm: TEmailDetailsForm;
KeyboardHook: HHook;
implementation
function KeyboardHookProc(Code: Integer; wParam, lParam: LongInt): LongInt; stdcall;
var
hWnd: THandle;
I: Integer;
F: TForm;
begin
if Code < 0 then
Result := CallNextHookEx(KeyboardHook, Code, wParam, lParam)
else begin
case wParam of
VK_ESCAPE:
if (lParam and $80000000) <> $00000000 then
begin
hWnd := GetForegroundWindow;
for I := 0 to Screen.FormCount - 1 do
begin
F := Screen.Forms[I];
if F.Handle = hWnd then
if F is TEmailDetailsForm then
begin
PostMessage(hWnd, WM_CLOSE, 0, 0);
Result := HC_SKIP;
break;
end;
end; //for
end; //if
else
Result := CallNextHookEx(KeyboardHook, Code, wParam, lParam);
end; //case
end; //if
end;
function TEmailDetailsForm.CheckInstance: Boolean;
var
I, J: Integer;
F: TForm;
begin
Result := false;
J := 0;
for I := 0 to Screen.FormCount - 1 do
begin
F := Screen.Forms[I];
if F is TEmailDetailsForm then
begin
J := J + 1;
if J = 2 then
begin
Result := true;
break;
end;
end;
end;
end;
procedure TEmailDetailsForm.FormCreate(Sender: TObject);
begin
if not CheckInstance then
KeyboardHook := SetWindowsHookEx(WH_KEYBOARD, #KeyboardHookProc, 0, GetCurrentThreadId());
end;
procedure TEmailDetailsForm.FormDestroy(Sender: TObject);
begin
if not CheckInstance then
UnHookWindowsHookEx(KeyboardHook);
end;

Answer 1

You could do this with TApplicationEvents.OnMessage instead. Drop a TApplicationEvents component on your application's main form with this code:
procedure TMainForm.ApplicationEvents1Message(var Msg: tagMSG;
var Handled: Boolean);
var
C: TControl;
H: HWND;
begin
if (Msg.message = WM_KEYDOWN) and (Msg.wParam = VK_ESCAPE) then begin
H := Msg.hwnd;
while GetParent(H) <> 0 do
H := GetParent(H);
C := FindControl(H);
if C is TEmailDetailsForm then begin
TEmailDetailsForm(C).Close;
Handled := True;
end;
end;
end;
If you want to keep using a keyboard hook instead, you should only hook it once, rather than once for each form, especially since you're overwriting a global variable. Try adding a HookCount global variable, and only hook/unhook if it's the only form.

Answer 2

The background: My form has a
TWebBrowser. I want to close the form
with ESC but the TWebBrowser eats the
keystrokes - so I decided to go with a
keyboard hook.
There might be a simpler solution. Have you tried setting the form's KeyPreview property to True?

Answer 3

Well, both forms are signed up to receive the keyboard notice, so they both close.
You need to put code in there to decide "is this ESC for me?". Maybe by determining if you're the window with focus or not. If it's not your ESCape, then don't close.
But, this all seems rather drastic. There must be a simpler, non-obtrusive way to detect the ESC within THIS APP, without having to monitor the keyboard for the whole system.