user32: Fix VK_RETURN handling in IsDialogMessage for dialogs without an IDOK.

dlls/user32/dialog.c

@@ -1221,10 +1221,8 @@ BOOL WINAPI IsDialogMessageW( HWND hwndDlg, LPMSG msg )
                 else if (DC_HASDEFID == HIWORD(dw = SendMessageW (hwndDlg, DM_GETDEFID, 0, 0)))
                 {
                     HWND hwndDef = GetDlgItem(hwndDlg, LOWORD(dw));
-                    if (!hwndDef || !IsWindowEnabled(hwndDef))
-                        return TRUE;
-                    SendMessageW( hwndDlg, WM_COMMAND, MAKEWPARAM( LOWORD(dw), BN_CLICKED ),
-                                    (LPARAM)GetDlgItem(hwndDlg, LOWORD(dw)));
+                    if (hwndDef ? IsWindowEnabled(hwndDef) : LOWORD(dw)==IDOK)
+                        SendMessageW( hwndDlg, WM_COMMAND, MAKEWPARAM( LOWORD(dw), BN_CLICKED ), (LPARAM)hwndDef);
                 }
                 else
                 {

dlls/user32/tests/dialog.c

@@ -1000,6 +1000,28 @@ static INT_PTR CALLBACK TestDefButtonDlgProc (HWND hDlg, UINT uiMsg,
     return FALSE;
 }
 
+static INT_PTR CALLBACK TestReturnKeyDlgProc (HWND hDlg, UINT uiMsg,
+        WPARAM wParam, LPARAM lParam)
+{
+    static int received_idok = 0;
+    switch (uiMsg)
+    {
+    case WM_INITDIALOG:
+        {
+            MSG msg = {hDlg, WM_KEYDOWN, VK_RETURN, 0x011c0001};
+            IsDialogMessage(hDlg, &msg);
+        }
+        ok(received_idok, "WM_COMMAND not received\n");
+        EndDialog(hDlg, 0);
+        return TRUE;
+    case WM_COMMAND:
+        ok(wParam==IDOK, "Expected IDOK\n");
+        received_idok = 1;
+        return TRUE;
+    }
+    return FALSE;
+}
+
 static void test_DialogBoxParamA(void)
 {
     INT_PTR ret;
@@ -1044,6 +1066,8 @@ static void test_DialogBoxParamA(void)
 
     ret = DialogBoxParamA(GetModuleHandle(NULL), "TEST_EMPTY_DIALOG", 0, TestDefButtonDlgProc, 0);
     ok(ret == IDOK, "Expected IDOK\n");
+
+    DialogBoxParamA(GetModuleHandle(NULL), "TEST_EMPTY_DIALOG", 0, TestReturnKeyDlgProc, 0);
 }
 
 static void test_DisabledDialogTest(void)