Where is the $IsContainer control located in 11.8?
There is no system attribute called IsContainer, which is what i infer from $IsContainer. Did you perhaps mean something different? There is no container control as such. Container is more a description of state. A note with children is a container. An agent with child aliases is also a container.
What are you doing that needs this ‘control’?
$IsContainer is a read-only Boolean which is true if a note has one or more children
I can’t find this in a v11.8.0 TBX. Is this a new app addition?
No: you are right, and I am wrong. $IsAgent exists, $IsContainer does not.
(It’s easy to test for the existence of a child note: $Path(child) will be true if there is at least one child note, and false otherwise.
Also, if $ChildCount is not zero, the note has children and is therefore currently a container:
if($ChildCount>0){ ....}