Hi velocitytoo,
your code is correct. However setting the “max” and “locked” properties on element initialization are not being applied as expected. This will also be fixed in the next release.
You can still set those properties after element initialization directly on the LayoutPanel item. For example:

docking.items[0].locked = true;
docking.items[0].max = 300;

If you have set an id to the LayoutPanel you can also target it via document.getElementById(id).
Best Regards,
Christopher
Smart HTML Elements Team
https://www.htmlelements.com