The disableToggle has cascading effect. When "disableToggle: true" is set on the top level ui-layout, it is also disabled for all ui-layout below it even when "disableToggle:false" are set on them.
See example here:
http://plnkr.co/edit/9TSQQxsTYGeZXPk7Msxh?p=preview
Please help! Thanks!