Possible to have a X close for a block ?

Is it possible to add a close cross on a HTML block ? I would like to create blocks that members can close when they see it on each page.

Possible ?

Yea. With some php code changes and the addition of some javascript it is possible. But not something we can just pull off the top of our head and post here. It would take some time to develop and test. It's a bit complex.

And before you ask, sorry, but no. I do not have time to do it right now. Very busy updating my modules.

This would be an idea for module to developp !