Input Navigation Issue in Subagent Prompt Editor

Question

**Bug Description**
When I am providing input for a subagent, I can't navigate backward to edit the text - after each keystroke my cursor is moved back to the end of the input box again, so I have to create the prompt outside the TUI and paste it in. 
I should be able to navigate forward/backward to add detail or restructure the prompt while editing it. 
Alternatively it would be nice to have a shortcut to open in $EDITOR – or to copy the text out, as I had to edit out the bars from the box arou