[MSGINA] gui: Remove superfluous DLG_DATA.TimerID (#2505)

And use a timer ID define, with a positive value; report SetTimer() failure.

dll/win32/msgina/gui.c

@@ -2,7 +2,7 @@
  * PROJECT:         ReactOS msgina.dll
  * FILE:            dll/win32/msgina/gui.c
  * PURPOSE:         ReactOS Logon GINA DLL
- * PROGRAMMERS:     Hervé Poussineau ([email protected])
+ * PROGRAMMERS:     Hervé Poussineau ([email protected])
  *                  Katayama Hirofumi MZ ([email protected])
  */
 
@@ -28,12 +28,14 @@ typedef struct _LEGALNOTICEDATA
     LPWSTR pszText;
 } LEGALNOTICEDATA, *PLEGALNOTICEDATA;
 
+// Timer ID for the animated dialog bar.
+#define IDT_BAR 1
+
 typedef struct _DLG_DATA
 {
     PGINA_CONTEXT pgContext;
     HBITMAP hLogoBitmap;
     HBITMAP hBarBitmap;
-    UINT_PTR TimerID;
     DWORD BarCounter;
     DWORD LogoWidth;
     DWORD LogoHeight;
@@ -191,7 +193,10 @@ StatusDialogProc(
 
             if (DlgData_LoadBitmaps(pDlgData))
             {
-                pDlgData->TimerID = SetTimer(hwndDlg, -1, 20, NULL);
+                if (SetTimer(hwndDlg, IDT_BAR, 20, NULL) == 0)
+                {
+                    ERR("SetTimer(IDT_BAR) failed: %d\n", GetLastError());
+                }
             }
             return TRUE;
         }
@@ -244,7 +249,7 @@ StatusDialogProc(
         {
             if (pDlgData && pDlgData->hBarBitmap)
             {
-                KillTimer(hwndDlg, pDlgData->TimerID);
+                KillTimer(hwndDlg, IDT_BAR);
             }
             DlgData_Destroy(pDlgData);
             return TRUE;