Find out what process registered a global hotkey? (Windows API)

One possible way is to use the Visual Studio tool Spy++.

Give this a try:

1. Run the tool (for me, it's at C:\Program Files (x86)\Microsoft Visual Studio\2017\Community\Common7\Tools\spyxx_amd64.exe)
2. In the menu bar, select Spy -> Log messages... (or hit Ctrl + M)
3. Check All Windows in System in the Additional Windows frame
4. Switch to the Messages tab
5. Click the Clear All button
6. Select WM_HOTKEY in the listbox, or check Keyboard in Message Groups (if you're OK with more potential noise)
7. Click the OK button
8. Press the hotkey in question (Win + R, for example)
9. Select the WM_HOTKEY line in the Messages (All Windows) window, right click, and select Properties... in the context menu
10. In the Message Properties dialog, click the Window Handle link (this will be the handle for the window that received the message)
11. Click the Synchronize button on the Window Properties dialog. This will show the window in the main Spy++ window treeview.
12. On the Window Properties dialog, select the Process tab
13. Click the Process ID link. This will show you the process (In my Win + R case: EXPLORER)

Your question piqued my interest, so I've done a bit of digging and while, unfortunately I don't have a proper answer for you, I thought I'd share what I have.

I found this example of creating keyboard hook (in Delphi) written in 1998, but is compilable in Delphi 2007 with a couple of tweaks.

It's a DLL with a call to SetWindowsHookEx that passes through a callback function, which can then intercept key strokes: In this case, it's tinkering with them for fun, changing left cursor to right, etc. A simple app then calls the DLL and reports back its results based on a TTimer event. If you're interested I can post the Delphi 2007 based code.

It's well documented and commented and you potentially could use it as a basis of working out where a key press is going. If you could get the handle of the application that sent the key strokes, you could track it back that way. With that handle you'd be able to get the information you need quite easily.

Other apps have tried determining hotkeys by going through their Shortcuts since they can contain a Shortcut key, which is just another term for hotkey. However most applications don't tend to set this property so it might not return much. If you are interested in that route, Delphi has access to IShellLink COM interface which you could use to load a shortcut up from and get its hotkey:

uses ShlObj, ComObj, ShellAPI, ActiveX, CommCtrl;

procedure GetShellLinkHotKey;
var
  LinkFile : WideString;
  SL: IShellLink;
  PF: IPersistFile;

  HotKey : Word;
  HotKeyMod: Byte;
  HotKeyText : string;
begin
  LinkFile := 'C:\Temp\Temp.lnk';

  OleCheck(CoCreateInstance(CLSID_ShellLink, nil, CLSCTX_INPROC_SERVER, IShellLink, SL));

  // The IShellLink implementer must also support the IPersistFile
  // interface. Get an interface pointer to it.
  PF := SL as IPersistFile;

  // Load file into IPersistFile object
  OleCheck(PF.Load(PWideChar(LinkFile), STGM_READ));

  // Resolve the link by calling the Resolve interface function.
  OleCheck(SL.Resolve(0, SLR_ANY_MATCH or SLR_NO_UI));

  // Get hotkey info
  OleCheck(SL.GetHotKey(HotKey));

  // Extract the HotKey and Modifier properties.
  HotKeyText := '';
  HotKeyMod := Hi(HotKey);

  if (HotKeyMod and HOTKEYF_ALT) = HOTKEYF_ALT then
    HotKeyText := 'ALT+';
  if (HotKeyMod and HOTKEYF_CONTROL) = HOTKEYF_CONTROL then
    HotKeyText := HotKeyText + 'CTRL+';
  if (HotKeyMod and HOTKEYF_SHIFT) = HOTKEYF_SHIFT then
    HotKeyText := HotKeyText + 'SHIFT+';
  if (HotKeyMod and HOTKEYF_EXT) = HOTKEYF_EXT then
    HotKeyText := HotKeyText + 'Extended+';

  HotKeyText := HotKeyText + Char(Lo(HotKey));

  if (HotKeyText = '') or (HotKeyText = #0) then
    HotKeyText := 'None';

  ShowMessage('Shortcut Key - ' + HotKeyText);
end;

If you've got access to Safari Books Online, there is a good section about working with shortcuts / shell links in the Borland Delphi 6 Developer's Guide by Steve Teixeira and Xavier Pacheco. My example above is a butchered version from there and this site.

Hope that helps!

After some research, it appears that you'd need to get access to the internal structure that MS uses to store the hotkeys. ReactOS has a clean room implementation that implements the GetHotKey call by iterating an internal list and extracting the hotkey that matches the parameters to the call.

Depending on how close ReactOS' implementation is to the MS implementation, you may be able to poke around in memory to find the structure, but that's over my head...

BOOL FASTCALL
GetHotKey (UINT fsModifiers,
           UINT vk,
           struct _ETHREAD **Thread,
           HWND *hWnd,
           int *id)
{
   PHOT_KEY_ITEM HotKeyItem;

   LIST_FOR_EACH(HotKeyItem, &gHotkeyList, HOT_KEY_ITEM, ListEntry)
   {
      if (HotKeyItem->fsModifiers == fsModifiers &&
            HotKeyItem->vk == vk)
      {
         if (Thread != NULL)
            *Thread = HotKeyItem->Thread;

         if (hWnd != NULL)
            *hWnd = HotKeyItem->hWnd;

         if (id != NULL)
            *id = HotKeyItem->id;

         return TRUE;
      }
   }

   return FALSE;
}

I presume this thread on sysinternals was asked by someone related to this question, but I thought I'd link to it anyway to keep the two together. The thread looks very intriguing, but I suspect that some deep dive spelunking would need to happen to figure this out without access to the MS internals.