Hi velocitytoo,
Disabling the floating of a LayoutPanel is currently not available but it will be added to our next release. You can follow our releases here or in our social media pages.
However, you can bind to the stateChange event and execute your custom code inside the handler when an item has been floated. You can remove the floated item from the DOM or dock it back inside if you wish via the API methods. Also you can get a list of all the items that are currently inside the DokcingLayout from the items getter. You can read more about it here API.
Best Regards,
Smart HTML Elements Team