However, the system continues to proceed to the action defined in the displayoption, instead of doing nothing. I've checked with print statements that this code is executing, and I've also checked that I've updated the variable properly. I've also tried setting system.vars.$L_ds_action, as well as just vars.$L_action. No succes. Am I missing something?
The display RAD Application is responsible for building many variables (like $L.action and $L.ds.action) and passing some of them to the Document Engine. The $L.ds.action variable is not built until after it executes the RAD Application tab.
Panel: process.option ---> Evaluate Pre Rad Expression and Pre JavsScript tabs
Panel: check.rad ---> Execute the RAD Application (if it is populated)