This is a modified version of slimbox, with a iframe support added.
Find:
this.eventPosition = this.position.bind(this);
Add a new line after it:
this.body = top.document.body;
Find:
.injectInside(document.body)
Replace with:
.injectInside(this.body)
Done.
Modified slimbox.js file can be download here:
[attach=140]