Usually, when you create a new pane, it is always added to the bottom or right of the list of panes. If you want to control the order in which the panes appear inside the TixPanedWindow widget, you can use the two optional parameters, -before and -after, for the add method. For example, the call:
will place the new pane immediately after pane1. The call:
.p add pane2 -after pane1
will place the new pane immediately in front of pane1.
.p add pane2 -before pane1