The J session is defined in script system\extras\util\jijs.ijs, which is loaded into locale jijs. You can customize this script if need be, or make use of the jijs utilities in your session. For example the following is a list of handles of the current open windows:
qsmall_jijs_''The following reads one of the windows:
+-------+------+-------+
|1246056|787212|1115058|
+-------+------+-------+
smread_jijs_ smsel_jijs_ '787212'
Tools Menu
You can add your own function key items to the Tools menu using menu
Edit|Configure...|Fkeys.