Is there a program (or command prompt) that can make my screen black or unresponsive until a key (e.g. "ü") is pressed?

I’ll put on Powershell again. In this particular case because of the easier accessibility than hybrid batch.

So I’ve already tried it with Power Shell, but my computer has such strong security precautions

Paranoia?

…that I’m just gonna crash him…

I would have liked to see the code….

The following Powershell hybrid batch does nothing more than

• to finish the Explorer/Desktop
• remove the frame and controls of the Powershell window
• resize the frameless window on screen size
• hide the Consolcursor
• and patiently wait until ü pressed
• the Explorer/Desktop is restarted

It does not use to close the powershell window via ALT+F4, as there is no desktop that accepts any user actions. (But it remains the way out via the monkey handle or reset)

No admin rights are required and no security policies are tanged! The batch can (unlike a Powershellscript) can easily be placed in the car start folder. (…or as a new REG_SZ value “Shell” under “HKEY_Current_User\Software\Microsoft\Windows NT\CurrentVersion\Winlogon” are entered as shell) !!!Preview!!! changing the standard shell (explorer) into a batch is not quite unproblematic and should only be done if tests do not show any problems… necessarily start the Explorer at the end!!

demo.cmd

<# : Batch Abschnitt Zeile nicht ändern
start ""  powershell "iex (gc '%~f0' -Encoding UTF8 -Raw | out-string)"
exit /b
: Ende Batch #>


taskkill /f /im "explorer.exe" #kill den Explorer ohne Autorestart (Stop-Process kann das  nicht ohne weiteres)
mode 20,10


$code = @"
[DllImport("user32.dll")] public static extern int GetWindowLong(IntPtr hWnd, int nIndex); 
[DllImport("user32.dll")] public static extern int SetWindowLong(IntPtr hWnd, int nIndex, int dwNewLong);
[DllImport("user32.dll")] public static extern bool SetWindowPos(IntPtr hWnd,IntPtr hWndInsertAfter, int X, int Y, int cx, int cy, uint uFlags); 
"@
$User32=Add-Type -MemberDefinition $code -Name Win32Util -Passthru
Add-Type -a System.Windows.Forms
$Display = [System.Windows.Forms.Screen]::PrimaryScreen.Bounds
$Hwnd=(Get-Process -ID $pid).MainWindowHandle
$CurrendStyle = $User32::GetWindowLong($Hwnd,-16)
$BorderlesStyle = $CurrendStyle -band -570163201
[void]$User32::SetWindowLong($Hwnd,-16, $BorderlesStyle)
[void]$User32::SetWindowPos($Hwnd,0,$Display.X,$Display.Y,$Display.Width,$Display.Height,0x20)


[console]::CursorVisible = $false
do{
    $keyInfo = [Console]::ReadKey($True)
} until ($keyInfo.KeyChar -eq 'ü')  #wait  for  Key 'ü'
explorer

as I said, the ding is a powershellscript, to which I just “trickreich” overwhelmed a “batch fur”. with it, I’m wearing all the obstacles in relation to Powershell.

Here is the Powershellscript without abbreviations and commented so that you can also see where any values come from and why I do certain things that you don’t expect in Powershell…

( -570163201 , 0x20 or -16 …etc is not necessarily plausible🥱)

Hide_Desktop.ps1

#.ps1-Dateien für  Powershell 5.1 mit Unicodezeichen (Umlauten) als UTF8 mit BOM Speichern!!!!

#define Flags
#https://learn.microsoft.com/en-us/windows/win32/winmsg/window-styles
[Flags()] enum WindowStyles {
    WS_BORDER = 0x800000
    WS_CAPTION = 0xc00000
    WS_CHILD = 0x40000000
    WS_CLIPCHILDREN = 0x2000000
    WS_CLIPSIBLINGS = 0x4000000
    WS_DISABLED = 0x8000000
    WS_DLGFRAME = 0x400000
    WS_GROUP = 0x20000
    WS_HSCROLL = 0x100000
    WS_MAXIMIZE = 0x1000000
    WS_MAXIMIZEBOX = 0x10000
    WS_MINIMIZE = 0x20000000
    WS_MINIMIZEBOX = 0x20000
    WS_OVERLAPPED = 0x0
    WS_POPUP = 0x80000000
    WS_THICKFRAME = 0x40000
    WS_SYSMENU = 0x80000
    WS_TABSTOP = 0x10000
    WS_VISIBLE = 0x10000000
    WS_VSCROLL = 0x200000
    WS_OVERLAPPEDWINDOW = 0 -bor 0xc00000 -bor 0x80000 -bor 0x40000 -bor 0x20000 -bor 0x10000
    WS_POPUPWINDOW = 0x80000000 -bor 0x800000 -bor 0x80000
}
#WS_OVERLAPPEDWINDOW = 0x00cf0000 (WS_OVERLAPPED | WS_CAPTION | WS_SYSMENU | WS_THICKFRAME | WS_MINIMIZEBOX | WS_MAXIMIZEBOX)
#WS_POPUPWINDOW = 0x80880000 (WS_POPUP | WS_BORDER | WS_SYSMENU)


#https://learn.microsoft.com/en-us/windows/win32/api/winuser/nf-winuser-setwindowlonga
[Flags()] enum GWL{
    GWL_WNDPROC = -4
    GWL_HINSTANCE = -6
    GWL_HWNDPARENT = -8
    GWL_STYLE = -16
    GWL_EXSTYLE = -20
    GWL_USERDATA = -21
    GWL_ID = -12
}


#https://learn.microsoft.com/en-us/windows/win32/winmsg/extended-window-styles
[Flags()] enum  ExtendedWindowStyles {
    WS_EX_DLGMODALFRAME = 0x0001
    WS_EX_NOPARENTNOTIFY = 0x0004
    WS_EX_TOPMOST = 0x0008
    WS_EX_ACCEPTFILES = 0x0010
    WS_EX_TRANSPARENT = 0x0020
    WS_EX_MDICHILD = 0x0040
    WS_EX_TOOLWINDOW = 0x0080
    WS_EX_WINDOWEDGE = 0x0100
    WS_EX_CLIENTEDGE = 0x0200
    WS_EX_CONTEXTHELP = 0x0400
    WS_EX_RIGHT = 0x1000
    WS_EX_LEFT = 0x0000
    WS_EX_RTLREADING = 0x2000
    WS_EX_LTRREADING = 0x0000
    WS_EX_LEFTSCROLLBAR = 0x4000
    WS_EX_RIGHTSCROLLBAR = 0x0000
    WS_EX_CONTROLPARENT = 0x10000
    WS_EX_STATICEDGE = 0x20000
    WS_EX_APPWINDOW = 0x40000
    WS_EX_OVERLAPPEDWINDOW = (0x0100 -bor 0x0200)
    WS_EX_PALETTEWINDOW = ( 0x100 -bor 0x80 -bor 0x8)
    WS_EX_LAYERED = 0x00080000
    WS_EX_NOINHERITLAYOUT = 0x00100000
    WS_EX_LAYOUTRTL = 0x00400000
    WS_EX_COMPOSITED = 0x02000000
    WS_EX_NOACTIVATE = 0x08000000
}
#WS_EX_OVERLAPPEDWINDOW = (WS_EX_WINDOWEDGE | WS_EX_CLIENTEDGE)
#WS_EX_PALETTEWINDOW = (WS_EX_WINDOWEDGE | WS_EX_TOOLWINDOW | WS_EX_TOPMOST)


#https://learn.microsoft.com/de-de/windows/win32/api/winuser/nf-winuser-setwindowpos#parameters
[Flags()] enum  SWPuFlags {
    SWP_NoSize = 0x0001
    SWP_NoMove = 0x0002
    SWP_NoZOrder = 0x0004
    SWP_NoRedraw = 0x0008
    SWP_NoActive = 0x0010
    SWP_FrameChanged = 0x0020
    SWP_ShowWindow = 0x0040
    SWP_HideWindow = 0x0080
    SWP_NoCopyBits = 0x0100
    SWP_NoOwnerZOrder = 0x0200
    SWP_NoReposition = 0x0200
    SWP_NoSendChanging = 0x0400
    SWP_DeferErase = 0x2000
    SWP_AsyncWindowPos = 0x4000
}


taskkill /f /im "explorer.exe" #kill Explorer without autorestart (Stop-Process works  not for Explorer)
mode 20,10 #use Batchcommand to  remove Quick&Dirty Screenbuffers/Scrollbars


 #define access to needed systemfunctions
$code = @"
    [DllImport("user32.dll")] public static extern int GetWindowLong(IntPtr hWnd, int nIndex); 
    [DllImport("user32.dll")] public static extern int SetWindowLong(IntPtr hWnd, int nIndex, int dwNewLong);
    [DllImport("user32.dll")] public static extern bool SetWindowPos(IntPtr hWnd,IntPtr hWndInsertAfter, int X, int Y, int cx, int cy, uint uFlags); 
"@
$User32=Add-Type -MemberDefinition $code -Name Win32Util -Passthru

Add-Type -a System.Windows.Forms
$Display = [System.Windows.Forms.Screen]::PrimaryScreen.Bounds #Size of Fullscreen

$Hwnd = (Get-Process -ID $pid).MainWindowHandle #this Window

$CurrendStyle = $User32::GetWindowLong($Hwnd,[GWL]::GWL_STYLE)
$BorderElementsOff = -bnot([WindowStyles]::WS_CAPTION -bor [WindowStyles]::WS_THICKFRAME -bor [WindowStyles]::WS_MINIMIZE -bor [WindowStyles]::WS_MAXIMIZE -bor [WindowStyles]::WS_SYSMENU -bor [WindowStyles]::WS_VSCROLL -bor [WindowStyles]::WS_HSCROLL)
$BorderlesStyle = $CurrendStyle -band $BorderElementsOff
 
[void]$User32::SetWindowLong($Hwnd,[GWL]::GWL_STYLE, $BorderlesStyle)
[void]$User32::SetWindowPos($Hwnd,0,$Display.X,$Display.Y,$Display.Width,$Display.Height,0x20)  #!!important!! SWP_FRAMECHANGED (0x0020)  to recalculate/redraw the clientarrea at fullsize 


[console]::CursorVisible = $false
do{
    $keyInfo = [Console]::ReadKey($true)
} until ($keyInfo.KeyChar -eq 'ü')


explorer   #restart Desktop