user32: DialogBoxParam should return -1 when dialog control creation fails.

dlls/user32/dialog.c

@@ -835,11 +835,12 @@ INT_PTR WINAPI DialogBoxParamA( HINSTANCE hInst, LPCSTR name,
     HRSRC hrsrc;
     LPCDLGTEMPLATEA ptr;
 
+    if (owner && !IsWindow(owner)) return 0;
+
     if (!(hrsrc = FindResourceA( hInst, name, (LPSTR)RT_DIALOG ))) return -1;
     if (!(ptr = LoadResource(hInst, hrsrc))) return -1;
-    hwnd = DIALOG_CreateIndirect( hInst, ptr, owner, dlgProc, param, FALSE, &owner );
-    if (hwnd) return DIALOG_DoDialogBox( hwnd, owner );
-    return 0;
+    if (!(hwnd = DIALOG_CreateIndirect( hInst, ptr, owner, dlgProc, param, FALSE, &owner ))) return -1;
+    return DIALOG_DoDialogBox( hwnd, owner );
 }
 
 
@@ -853,11 +854,12 @@ INT_PTR WINAPI DialogBoxParamW( HINSTANCE hInst, LPCWSTR name,
     HRSRC hrsrc;
     LPCDLGTEMPLATEW ptr;
 
+    if (owner && !IsWindow(owner)) return 0;
+
     if (!(hrsrc = FindResourceW( hInst, name, (LPWSTR)RT_DIALOG ))) return -1;
     if (!(ptr = LoadResource(hInst, hrsrc))) return -1;
-    hwnd = DIALOG_CreateIndirect( hInst, ptr, owner, dlgProc, param, TRUE, &owner );
-    if (hwnd) return DIALOG_DoDialogBox( hwnd, owner );
-    return 0;
+    if (!(hwnd = DIALOG_CreateIndirect( hInst, ptr, owner, dlgProc, param, TRUE, &owner ))) return -1;
+    return DIALOG_DoDialogBox( hwnd, owner );
 }
 
 

dlls/user32/tests/dialog.c

@@ -1273,7 +1273,6 @@ static void test_DialogBoxParamA(void)
 
     SetLastError(0xdeadbeef);
     ret = DialogBoxParamA(GetModuleHandleA(NULL), "TEST_DIALOG_INVALID_CLASS", 0, DestroyDlgWinProc, 0);
-todo_wine
     ok(ret == -1, "DialogBoxParamA returned %ld, expected -1\n", ret);
     ok(GetLastError() == 0, "got %d\n", GetLastError());