[SHELL32][SDK] Implement SHIsTempDisplayMode (#5523)

CORE-9277

dll/win32/shell32/shelldesktop/CDesktopBrowser.cpp

@@ -520,3 +520,33 @@ BOOL WINAPI SHDesktopMessageLoop(HANDLE hDesktop)
 
     return TRUE;
 }
+
+/*************************************************************************
+ *  SHIsTempDisplayMode [SHELL32.724]
+ *
+ * Is the current display settings temporary?
+ */
+EXTERN_C BOOL WINAPI SHIsTempDisplayMode(VOID)
+{
+    TRACE("\n");
+
+    if (GetSystemMetrics(SM_REMOTESESSION) || GetSystemMetrics(SM_REMOTECONTROL))
+        return FALSE;
+
+    DEVMODEW DevMode;
+    ZeroMemory(&DevMode, sizeof(DevMode));
+    DevMode.dmSize = sizeof(DevMode);
+
+    if (!EnumDisplaySettingsW(NULL, ENUM_REGISTRY_SETTINGS, &DevMode))
+        return FALSE;
+
+    if (!DevMode.dmPelsWidth || !DevMode.dmPelsHeight)
+        return FALSE;
+
+    HDC hDC = GetDC(NULL);
+    DWORD cxWidth = GetDeviceCaps(hDC, HORZRES);
+    DWORD cyHeight = GetDeviceCaps(hDC, VERTRES);
+    ReleaseDC(NULL, hDC);
+
+    return (cxWidth != DevMode.dmPelsWidth || cyHeight != DevMode.dmPelsHeight);
+}

dll/win32/shell32/stubs.cpp

@@ -130,17 +130,6 @@ GetFileDescriptor(FILEGROUPDESCRIPTOR *pFileGroupDesc, BOOL bUnicode, INT iIndex
     return NULL;
 }
 
-/*
- * Unimplemented
- */
-EXTERN_C BOOL
-WINAPI
-SHIsTempDisplayMode(VOID)
-{
-    FIXME("SHIsTempDisplayMode() stub\n");
-    return FALSE;
-}
-
 /*
  * Unimplemented
  */

sdk/include/reactos/undocshell.h

@@ -189,6 +189,8 @@ DWORD WINAPI SHNetConnectionDialog(
     LPCWSTR lpstrRemoteName,
     DWORD dwType);
 
+BOOL WINAPI SHIsTempDisplayMode(VOID);
+
 /****************************************************************************
  * Cabinet Window Messages
  */