Thanks Merlyn, that is exactly the answer I was looking for in theory (but I'm yet to test it). But it seems right. This is what I thought was happening but I wasn't sure how to resolve it. I have to race out the door now and will test this tomorrow, or later tonight. Two preliminary question that I'm sure I'll answer later anyway in testing:

1. Do you write this into your Mainloop or into the end of the subroutine.
2. Which widget is it assigned to? MainWindow or the text box?

No biggy if you don't answer. It will only take me a few mins to work it out, but I have to race now. I'll post an update, conclusion and discussional results with my findings at the end of all this.