user32: Report a fake monitor when running on an invisible window station.

dlls/user32/sysparams.c

@@ -4111,12 +4111,20 @@ static BOOL CALLBACK enum_mon_callback( HMONITOR monitor, HDC hdc, LPRECT rect,
 
 BOOL CDECL nulldrv_EnumDisplayMonitors( HDC hdc, RECT *rect, MONITORENUMPROC proc, LPARAM lp )
 {
+    BOOL is_winstation_visible = FALSE;
+    USEROBJECTFLAGS flags;
+    HWINSTA winstation;
     RECT monitor_rect;
     DWORD i = 0;
 
     TRACE("(%p, %p, %p, 0x%lx)\n", hdc, rect, proc, lp);
 
-    if (update_monitor_cache())
+    /* Report physical monitor information only if window station has visible display surfaces */
+    winstation = GetProcessWindowStation();
+    if (GetUserObjectInformationW( winstation, UOI_FLAGS, &flags, sizeof(flags), NULL ))
+        is_winstation_visible = flags.dwFlags & WSF_VISIBLE;
+
+    if (is_winstation_visible && update_monitor_cache())
     {
         while (TRUE)
         {

dlls/user32/tests/monitor.c

@@ -1563,6 +1563,7 @@ static void test_EnumDisplayMonitors(void)
     static const DWORD DESKTOP_ALL_ACCESS = 0x01ff;
     HWINSTA winstation, old_winstation;
     HDESK desktop, old_desktop;
+    USEROBJECTFLAGS flags;
     INT count, old_count;
     DWORD error;
     BOOL ret;
@@ -1602,6 +1603,12 @@ static void test_EnumDisplayMonitors(void)
     ok(ret, "SetProcessWindowStation failed, error %#x.\n", GetLastError());
     ok(winstation == GetProcessWindowStation(), "Expected %p, got %p.\n", GetProcessWindowStation(), winstation);
 
+    flags.fInherit = FALSE;
+    flags.fReserved = FALSE;
+    flags.dwFlags = WSF_VISIBLE;
+    ret = SetUserObjectInformationW(winstation, UOI_FLAGS, &flags, sizeof(flags));
+    ok(ret, "SetUserObjectInformationW failed, error %#x.\n", GetLastError());
+
     desktop = CreateDesktopW(L"test_desktop", NULL, NULL, 0, DESKTOP_ALL_ACCESS, NULL);
     ok(!!desktop && desktop != old_desktop, "CreateDesktopW failed, error %#x.\n", GetLastError());
     ret = SetThreadDesktop(desktop);