Clearing TextFlow selection

How can I forcibly clear all selections and caret cursors from a TextFlow?  There are no methods in SelectionManager that accomplish this.  SelectionManager.selectRange() selects a range - but how do I unselect EVERYTHING?

I need to force a TextFlow (ie. associated Containers) NOT to show any selections or caret cursors.  I only want one TextFlow to appear to have keyboard focus.

I have an application with more than one TextFlow on the screen.  Everything works fine when I test the application in the browser (apart from a small problem setting focus initially - that doesn't happen in AIR), but when I build it as an AIR application I get multiple flashing carets or selections on the screen.  One for each TextFlow.