Just made interesting discovery and it could be useful for someone.
Well,it goes like this:

When you create mouse over something and add alternative text in mouseover object properties but not in original object properties,then tag for that object does not show up in web page but exist in page code.
Its handy for adding hidden text for search engine or for something,probably.

And again same question like my first post:
How can i use different language in VSD?
Help,anyone?

Some Browsers stopped displaying the "alt" tag a long time ago, you can however use the "title" tag with images, although this is normally used within a link.

I'm sorry this discovery isn't true,my mistake.
Sorry again.

But tags works in Mozilla and IE so far,used in regular way.

Title tags are another SEO tool, if used wisely.