Warning: Icon load event was not propagated because VCaption owner is unkn

Just started playing with the ?debug option and noted that error was on the initial load of my app:

Warning: Icon load event was not propagated because VCaption owner is unknown.

What might that be? Is there anything to be concerned about? I am trying to track down why a Form in an initial TabSheet renders fine, but when opened in additional TabSheets, horizontal scrollbars appear, but not sure how to read the debug info it’s producing.