Our site has a few custom page validator, like:

public class BasePageValidator : IValidate
{
    IEnumerable 
    IValidate.Validate(BasePage basePage)
    {
        ...
    }
}

One of those validator make sure you cannot publish a page that references an image without an alt text, and the alt text is a property on the image object.

Typical usecase:
1) Editor tries to publish page A
2) Validator message says that image with id 123 must have alt text
3) Editor opens image with id 123 in a separate browser tab, and updates the alt text
4) Editor returns to the tab with page A, the validator error is still visble
5) Editor is unable to publish the page

A workaround is refreshing the entire page or updating a property. 

Our feature request is that clicking the publish button revalidates the page, at least if it page has validation errors.

As simple as: