Unfortunately screen shots can not be taken of this condition using Jing so I listed the steps to recreate it
In the BB settings window:
1. select Add Stop Loss
2 select Custom
3. Open the custom Options window >> Trading Actions tab
4.set mode to Custom and add a new trading rule
5. The Action entry is where the window gets left open
a. action = Move to Last
b in the Move Relative selection panel select the down arrow on Last
c. this should open another window "Select Mode"
6. At this point move the mouse back to the Order set Stop Custom section and press the left mouse button. All of the other open windows will close except the last one opened (Select Mode). It appears that it will stay opened until closed manually.
Maybe it is supposed to work that way however, my belief is that one intentionally selects something outside of the area being worked on then no action was dwesired other than to cancel the in-process operation.