Lock webimage o container control

I have some issues using the locks on webcontainers. Locking into the webcontainer controls like webimages or child containers doesn’t work as expected.
Example:
Webcontainer A containing a webimage. The web image is locked top-right into the webcontainer A.
Webcontainer A is locked into webpage left-top-right.
Result showing the page: webcontainer resize to the height of to the page. The webimage inside the webcontainer A go out of scope and is visible only scrolling to the right with scrollbars.
I don’t want to show any scrollbar into container.
Where I’m doing wrong ?
Thanks.
C