This might have been covered but I can't find it by searching so sorry if it's a duplicate. It applies to Web Designer v11, possibly others and the Zaccordian1 slider widget, likely the others too.

If you've ever opened up your project to be met with a pop-up saying...
Warning
Problems detected in document:
Found shadow group with no shadowed object. A black rectangle with name "Validate_Changed" has been inserted in place of the missing object.

... the last sentence possibly repeated a few times.

it may be due to removing the text from your Zaccordian slider widget without deleting the accompanying shadow (like I did).

It's better not to use the text tool if you want to delete the vertical text. Instead, go into the Page and Layout gallery, expand the groups for each page/image until you see the shadow group, then delete the shadow group (which includes the text) That will delete both the text and it's shadow.

If you just delete the text with the text tool after changing the example images, all will seem fine, but the next time you open the .web file you will get the above-mentioned warning box.

If you delete the text then copy the new images over the example ones before saving the widget, all except the first image/page will be fine, but that will be enough to trigger the warning next time round.

If you delete the text with the text tool (and click on another page/image), then (in the Page and Layout gallery) expand the groups to the deleted text, you will get 'Internal program error 1955.k.no.nt'. Possibly lots of them.

It's not serious because the error routine keeps your .web file uncorrupted so you can go in any time to delete any remaining shadow groups and all will be well again. Thank you black rectangles (and whoever writes proper error routines).