RegisterPostMessageHook not working when run as Admin

[MiloLug]

When I run my script as Administrator, RegisterPostMessageHook does nothing. No error, just nothing happens.

Here's some minimal example:

#Requires AutoHotkey v2.0

#SingleInstance Force
Persistent

SetWorkingDir(A_ScriptDir)

MSG_VIRTUAL_DESKTOP_MENAGER := 0x1400 + 30

_hVD := DllCall("LoadLibrary", "Str", ".\WindowManagement\VirtualDesktopAccessor.dll", "Ptr")
_hProcRegisterPostMessageHook := DllCall("GetProcAddress", "Ptr", _hVD, "AStr", "RegisterPostMessageHook", "Ptr")

if (!DllCall("ChangeWindowMessageFilterEx", "Ptr", A_ScriptHwnd, "UInt", MSG_VIRTUAL_DESKTOP_MENAGER, "UInt", 1, "Ptr", 0, "Int")) {  ; MSGFLT_ALLOW
    MsgBox("Can't change filter EX")
}

; To be COMPLETELY sure
if (!DllCall("ChangeWindowMessageFilter", "UInt", MSG_VIRTUAL_DESKTOP_MENAGER, "UInt", 1, "Int")) {  ; MSGFLT_ADD
    MsgBox("Can't change filter")
}

if (DllCall(_hProcRegisterPostMessageHook, "Ptr", A_ScriptHwnd, "Int", MSG_VIRTUAL_DESKTOP_MENAGER, "Int") == -1) {
    MsgBox("Can't register post message hook")
}

OnMessage(MSG_VIRTUAL_DESKTOP_MENAGER, recipient)
recipient(prevDesktop, newDesktop, msg, hwnd) {
    ; Not triggered from Admin
    MsgBox("VDM: prev>" prevDesktop " new>" newDesktop " msg>" msg " hwnd>" hwnd)
}

I already know it's not a separate process, so I don't really need ChangeWindowMessageFilterEx, but added it just to make sure it isn't some kind of a messaging problem.
I guess it's something to do with COM access, but I'm no expert at that level.

• Sytem: win 11, 24H2, 26100.4946
• Users:
  My main user is NOT an admin. When I run the script as admin, it goes through the UAC, and it's technically being run from a different user, not just elevated (I guess..)

[tje3d]

Its not working on 24H2, 26100.4652 as well

[Ciantic]

Hmm I have 26100.6584 everything worked just like before for me.

[tje3d]

Hmm I have 26100.6584 everything worked just like before for me.

Sorry, Looks like I have a different issue: I can’t load the DLL in my AutoHotkey script. Here’s the code.
Any idea how to fix it?

Version: 24H2
OS Build: 26100.2605
Windows Feature Experience Pack 1000.26100.36.0

#Requires AutoHotkey v2
#UseHook
#SingleInstance Force

; --------------------------------------------------------------
; 1️⃣  INITIAL SETUP
; --------------------------------------------------------------
SetWorkingDir(A_ScriptDir)

if !A_IsAdmin {
    try Run('*RunAs "' A_ScriptFullPath '" /restart')
    ExitApp
}

; -------------------------------------------------------------
; Load VirtualDesktopAccessor.dll and cache the required functions
; -------------------------------------------------------------
VDA_PATH := A_ScriptDir . "\VirtualDesktopAccessor.dll"
hVirtualDesktopAccessor := DllCall("LoadLibrary", "Str", VDA_PATH, "Ptr")

if (!hVirtualDesktopAccessor) {
    MsgBox("DLL could not be loaded – wrong architecture?", "Fail", 0x10)
    ExitApp
}

[tje3d]

Hmm I have 26100.6584 everything worked just like before for me.

Sorry, Looks like I have a different issue: I can’t load the DLL in my AutoHotkey script. Here’s the code. Any idea how to fix it?

Version: 24H2 OS Build: 26100.2605 Windows Feature Experience Pack 1000.26100.36.0

#Requires AutoHotkey v2
#UseHook
#SingleInstance Force

; --------------------------------------------------------------
; 1️⃣ INITIAL SETUP
; --------------------------------------------------------------
SetWorkingDir(A_ScriptDir)

if !A_IsAdmin {
try Run('*RunAs "' A_ScriptFullPath '" /restart')
ExitApp
}

; -------------------------------------------------------------
; Load VirtualDesktopAccessor.dll and cache the required functions
; -------------------------------------------------------------
VDA_PATH := A_ScriptDir . "\VirtualDesktopAccessor.dll"
hVirtualDesktopAccessor := DllCall("LoadLibrary", "Str", VDA_PATH, "Ptr")

if (!hVirtualDesktopAccessor) {
MsgBox("DLL could not be loaded – wrong architecture?", "Fail", 0x10)
ExitApp
}

Oh, my bad—I was missing the Microsoft Visual C++ 2015-2022 Redistributable (x64). After installing it, the DLL loads without any problems on both 26100.2605 and 26100.4652.

Here is full code, This script enables switching between virtual desktops using Alt+1-0 keys while preserving the active window on each desktop

#Requires AutoHotkey v2
#UseHook
#SingleInstance Force

; --------------------------------------------------------------
; 1️⃣  INITIAL SETUP
; --------------------------------------------------------------
SetWorkingDir(A_ScriptDir)

if !A_IsAdmin {
    try Run('*RunAs "' A_ScriptFullPath '" /restart')
    ExitApp
}

; --------------------------------------------------------------
; 2️⃣  LOAD VIRTUAL DESKTOP ACCESSOR DLL
; --------------------------------------------------------------
VDA_PATH := A_ScriptDir . "\VirtualDesktopAccessor.dll"
hVirtualDesktopAccessor := DllCall("LoadLibrary", "Str", VDA_PATH, "Ptr")

if (!hVirtualDesktopAccessor) {
    MsgBox("DLL could not be loaded – wrong architecture?", "Fail", 0x10)
    ExitApp
}

GetDesktopCountProc := DllCall("GetProcAddress", "Ptr", hVirtualDesktopAccessor, "AStr", "GetDesktopCount", "Ptr")
GoToDesktopNumberProc := DllCall("GetProcAddress", "Ptr", hVirtualDesktopAccessor, "AStr", "GoToDesktopNumber", "Ptr")
GetCurrentDesktopNumberProc := DllCall("GetProcAddress", "Ptr", hVirtualDesktopAccessor, "AStr",
    "GetCurrentDesktopNumber", "Ptr")
IsWindowOnDesktopNumberProc := DllCall("GetProcAddress", "Ptr", hVirtualDesktopAccessor, "AStr",
    "IsWindowOnDesktopNumber", "Ptr")
MoveWindowToDesktopNumberProc := DllCall("GetProcAddress", "Ptr", hVirtualDesktopAccessor, "AStr",
    "MoveWindowToDesktopNumber", "Ptr")
GetDesktopNameProc := DllCall("GetProcAddress", "Ptr", hVirtualDesktopAccessor, "AStr", "GetDesktopName", "Ptr")
SetDesktopNameProc := DllCall("GetProcAddress", "Ptr", hVirtualDesktopAccessor, "AStr", "SetDesktopName", "Ptr")
CreateDesktopProc := DllCall("GetProcAddress", "Ptr", hVirtualDesktopAccessor, "AStr", "CreateDesktop", "Ptr")
RemoveDesktopProc := DllCall("GetProcAddress", "Ptr", hVirtualDesktopAccessor, "AStr", "RemoveDesktop", "Ptr")
RegisterPostMessageHookProc := DllCall("GetProcAddress", "Ptr", hVirtualDesktopAccessor, "AStr",
    "RegisterPostMessageHook", "Ptr")
UnregisterPostMessageHookProc := DllCall("GetProcAddress", "Ptr", hVirtualDesktopAccessor, "AStr",
    "UnregisterPostMessageHook", "Ptr")

GetDesktopCount() {
    global GetDesktopCountProc
    return DllCall(GetDesktopCountProc, "Int")
}
GetCurrentDesktopNumber() {
    global GetCurrentDesktopNumberProc
    return DllCall(GetCurrentDesktopNumberProc, "Int")
}

; --------------------------------------------------------------
; 3️⃣  MAP: DESKTOP # (0-BASED) → HWND OF THE LAST-FOCUSED WINDOW
; --------------------------------------------------------------
global LastActiveWin := Map()   ; stores the "last active window" per desktop

; --------------------------------------------------------------
; 4️⃣  LIST OF WINDOW CLASSES WE NEVER WANT TO ACTIVATE
; --------------------------------------------------------------
IgnoredClasses := Map(
    "Shell_TrayWnd", true,
    "Shell_SecondaryTrayWnd", true,
    "Progman", true,
    "WorkerW", true
)   ; A map works as a set (the value `true` isn't used)

; --------------------------------------------------------------
; 5️⃣  HELPER: DOES A WINDOW BELONG TO THE IGNORE-LIST?
; --------------------------------------------------------------
IsIgnoredWindow(hwnd) {
    className := WinGetClass("ahk_id " . hwnd)
    return IgnoredClasses.Has(className)   ; "Has" checks for the key, i.e. the class name
}

; --------------------------------------------------------------
; 6️⃣  STORE THE ACTIVE WINDOW FOR THE CURRENT DESKTOP BEFORE WE LEAVE IT
; --------------------------------------------------------------
SaveActiveWindowForCurrentDesktop() {
    global LastActiveWin
    try {
        active := WinGetID("A")
        if (!active)          ; nothing to store
            return
        if (IsIgnoredWindow(active))   ; don't store the task-bar or other system wnd
            return
        curDesk := GetCurrentDesktopNumber()
        LastActiveWin[curDesk] := active
    } catch {
        ; silently ignore any error (e.g. no active window)
    }
}

; --------------------------------------------------------------
; 7️⃣  ACTIVATE THE REMEMBERED WINDOW FOR A GIVEN DESKTOP,
;      OR FALL BACK TO THE FIRST "REAL" WINDOW WE CAN FIND
; --------------------------------------------------------------
ActivateWindowOnDesktop(deskNum) {
    global LastActiveWin, IsWindowOnDesktopNumberProc

    ; ----- Try the remembered HWND first ---------------------------------
    if LastActiveWin.Has(deskNum) {
        hwnd := LastActiveWin[deskNum]
        if (WinExist("ahk_id " hwnd)                 ; still alive?
        && DllCall(IsWindowOnDesktopNumberProc, "Ptr", hwnd, "Int", deskNum, "Int")   ; still on this desktop?
        && !IsIgnoredWindow(hwnd)) {            ; make sure it's not the task-bar
            WinActivate("ahk_id " hwnd)
            ; Optional: hide task-bar again if you hide it with WinHide
            ; (uncomment the next two lines if you use a manual-hide script)
            ; if (tb := WinExist("ahk_class Shell_TrayWnd"))
            ;     WinHide("ahk_id " tb)
            return
        }
        ; If the saved hwnd is no longer usable, drop it.
        LastActiveWin.Delete(deskNum)
    }

    ; ----- No remembered window – look for the first "real" one ----------
    for hwnd in WinGetList() {
        ; Must be visible…
        if (!DllCall("IsWindowVisible", "Ptr", hwnd))
            continue
        ; …and must belong to the target desktop…
        if (!DllCall(IsWindowOnDesktopNumberProc, "Ptr", hwnd, "Int", deskNum, "Int"))
            continue
        ; …and must NOT be a system window we want to ignore.
        if (IsIgnoredWindow(hwnd))
            continue
        ; That's a good candidate.
        WinActivate("ahk_id " hwnd)
        ; Optional: hide task-bar again (same comment as above)
        ; if (tb := WinExist("ahk_class Shell_TrayWnd"))
        ;     WinHide("ahk_id " tb)
        break
    }
}

; --------------------------------------------------------------
; 8️⃣  MOVE THE CURRENTLY ACTIVE WINDOW TO ANOTHER DESKTOP (SHIFT+WIN+X)
; --------------------------------------------------------------
MoveCurrentWindowToDesktop(number) {
    global MoveWindowToDesktopNumberProc, GoToDesktopNumberProc, LastActiveWin

    activeHwnd := WinGetID("A")
    if (!activeHwnd)
        return

    ; Do not move the task-bar (should never happen, but just in case)
    if (IsIgnoredWindow(activeHwnd))
        return

    ; Move the window
    DllCall(MoveWindowToDesktopNumberProc, "Ptr", activeHwnd, "Int", number, "Int")
    ; Remember it as the "last active" window for the destination desktop
    LastActiveWin[number] := activeHwnd

    ; Switch to the target desktop so the user sees the moved window
    DllCall(GoToDesktopNumberProc, "Int", number, "Int")
}

; --------------------------------------------------------------
; 9️⃣  WRAPPER THAT DECIDES WHETHER TO MOVE THE WINDOW (SHIFT HELD)
;      OR JUST GO TO THE DESKTOP. ALSO RECORDS THE OLD ACTIVE WINDOW.
; --------------------------------------------------------------
MoveOrGotoDesktopNumber(num) {
    ; Remember which window was active on the desktop we are leaving.
    SaveActiveWindowForCurrentDesktop()

    if (GetKeyState("LButton")) {
        MoveCurrentWindowToDesktop(num)
        ; The moved window already got focus, nothing more to do.
        return
    } else {
        GoToDesktopNumber(num)
        ; After the desktop switch finishes, reactivate the stored window.
        ; A short timer gives the system a moment to finish the switch.
        SetTimer(() => ActivateWindowOnDesktop(num), -120)   ; 120 ms delay
        return
    }
}

; --------------------------------------------------------------
; 1️⃣0️⃣  SIMPLE WRAPPERS FOR CHANGING DESKTOPS
; --------------------------------------------------------------
GoToDesktopNumber(num) {
    global GoToDesktopNumberProc
    DllCall(GoToDesktopNumberProc, "Int", num, "Int")
}
GoToPrevDesktop() {
    current := GetCurrentDesktopNumber()
    last := GetDesktopCount() - 1
    if (current = 0)
        MoveOrGotoDesktopNumber(last)
    else
        MoveOrGotoDesktopNumber(current - 1)
}
GoToNextDesktop() {
    current := GetCurrentDesktopNumber()
    last := GetDesktopCount() - 1
    if (current = last)
        MoveOrGotoDesktopNumber(0)
    else
        MoveOrGotoDesktopNumber(current + 1)
}

; --------------------------------------------------------------
; 1️⃣1️⃣  DESKTOP-NAME HELPERS
; --------------------------------------------------------------
GetDesktopName(num) {
    global GetDesktopNameProc
    utf8_buffer := Buffer(1024, 0)
    DllCall(GetDesktopNameProc, "Int", num, "Ptr", utf8_buffer, "Ptr", utf8_buffer.Size, "Int")
    return StrGet(utf8_buffer, "UTF-8")
}
SetDesktopName(num, name) {
    global SetDesktopNameProc
    name_utf8 := Buffer(1024, 0)
    StrPut(name, name_utf8, "UTF-8")
    DllCall(SetDesktopNameProc, "Int", num, "Ptr", name_utf8, "Int")
}

; --------------------------------------------------------------
; 1️⃣2️⃣  DESKTOP CREATION / REMOVAL
; --------------------------------------------------------------
CreateDesktop() {
    global CreateDesktopProc
    DllCall(CreateDesktopProc, "Int")
}
RemoveDesktop(remove_desktop_number, fallback_desktop_number) {
    global RemoveDesktopProc
    DllCall(RemoveDesktopProc, "Int", remove_desktop_number, "Int", fallback_desktop_number, "Int")
}

; --------------------------------------------------------------
; 1️⃣3️⃣  REGISTER FOR THE POST-MESSAGE THAT NOTIFIES US A DESKTOP HAS CHANGED
;        (MOSTLY FOR DEBUG OUTPUT – THE REAL ACTIVATION LOGIC LIVES IN
;        MOVEORGOTODESKTOPNUMBER / ACTIVATEWINDOWONDESKTOP)
; --------------------------------------------------------------
DllCall(RegisterPostMessageHookProc, "Ptr", A_ScriptHwnd, "Int", 0x1400 + 30, "Int")
OnMessage(0x1400 + 30, OnChangeDesktop)
OnChangeDesktop(wParam, lParam, msg, hwnd) {
    Critical(1)
    OldDesktop := wParam + 1
    NewDesktop := lParam + 1
    Name := GetDesktopName(NewDesktop - 1)

    OutputDebug("Desktop changed to " Name " from " OldDesktop " to " NewDesktop)
    ; If you ever use the built-in Win+Ctrl+←/→ shortcuts you could also
    ; call ActivateWindowOnDesktop(NewDesktop-1) here – the same logic as
    ; MoveOrGotoDesktopNumber already does that for the hot-keys.
}

; --------------------------------------------------------------
; 1️⃣4️⃣  HOT-KEYS – THEY ALL GO THROUGH MOVEORGOTODESKTOPNUMBER,
;         SO THE FOCUS-REMEMBERING WORKS AUTOMATICALLY
; --------------------------------------------------------------
!1:: MoveOrGotoDesktopNumber(0)
!2:: MoveOrGotoDesktopNumber(1)
!3:: MoveOrGotoDesktopNumber(2)
!4:: MoveOrGotoDesktopNumber(3)
!5:: MoveOrGotoDesktopNumber(4)
!6:: MoveOrGotoDesktopNumber(5)
!7:: MoveOrGotoDesktopNumber(6)
!8:: MoveOrGotoDesktopNumber(7)
!9:: MoveOrGotoDesktopNumber(8)
!0:: MoveOrGotoDesktopNumber(9)