Hello,
for grid columns there is an opportunity to set column errors with Row.SetColumnError().
Does anybody know if there is a similar opportunity for the toolbarsmanager, which can show errors right behind a tool?
This is currently not possible with the UltraToolbarsManager. I have submitted this as a new Product Idea to our product management team. I have also created a support case and provided more details on the product idea through the case.