Delphi application - Block windows-key (Start) on Windows 8 - windows

Question

I' programming a Delphi application. My goal is to cover ALL screen with my application to force user to fill my form. Application will be run as scheduled task.
My problem is, that normally, Windows does not allow applications to block other users action.
In Windows 7 I can run my application as scr file (screen saver), with no title bar and set StayOnTop. In this case, other application even if visible on "Window key" (start), stays behind my application, so my goal is reached.
Unfortunately, in Windows 8 this solution does not work because "window key" shows start screen, when I can run anything and this "anything" stays on top.
I tried some trick with code below, but without success.
h := FindWindowEx(FindWindow('Shell_TrayWnd', nil),0,'Button',nil);
ShowWindow(h,0);
Windows.SetParent(h,0);
How to block 'window key' (start button) action in the entire Windows 8 system?

Answer 1

I didn't test it on windows 8, but in principle one can use a keyboard hook to discard the key-press.
Something similar to the following:
const
WH_KEYBOARD_LL = 13;
LLKHF_ALTDOWN = $00000020;
LLKHF_INJECTED = $00000010;
type
tagKBDLLHOOKSTRUCT = record
vkCode: DWORD;
scanCode: DWORD;
flags: DWORD;
time: DWORD;
dwExtraInfo: DWORD;
end;
KBDLLHOOKSTRUCT = tagKBDLLHOOKSTRUCT;
LPKBDLLHOOKSTRUCT = ^KBDLLHOOKSTRUCT;
PKBDLLHOOKSTRUCT = ^KBDLLHOOKSTRUCT;
var
hhkLowLevelKybd: HHOOK;
function LowLevelKeyBoardProc(nCode: Integer; awParam: WPARAM; alParam: LPARAM): LRESULT; stdcall;
var
fEatKeyStroke: Boolean;
p: PKBDLLHOOKSTRUCT;
begin
fEatKeystroke := False;
if active and( nCode = HC_ACTION) then
begin
case awParam of
WM_KEYDOWN,
WM_SYSKEYDOWN,
WM_KEYUP,
WM_SYSKEYUP:
begin
p := PKBDLLHOOKSTRUCT(alParam);
if DisableWinKeys then
begin
if p^.vkCode = VK_LWIN
then fEatKeystroke := True;
if p^.vkCode = VK_RWIN
then fEatKeystroke := True;
end;
end;
end;
end;
if fEatKeyStroke then
Result := 1
else
Result := CallNextHookEx(hhkLowLevelKybd, nCode, awParam, alParam);
end;
procedure InstallHook;
begin
if hhkLowLevelKybd <> 0 then exit;
hhkLowLevelKybd := SetWindowsHookEx(WH_KEYBOARD_LL, #LowLevelKeyboardProc, hInstance, 0);
end;
procedure UninstallHook;
begin
if hhkLowLevelKybd = 0 then exit;
UnhookWindowsHookEx(hhkLowLevelKybd);
hhkLowLevelKybd := 0;
end;