In SoapUI 4.x, the navigation pane used to rememer it's last saved width between sessions. However, Ready! API does not remember this type of sizing information--every time you restart the app, the pans are back to their default sizes.
Please enhance Ready! API so that all of the panes and view windows remember their last sizes. Everything is resizable, but it's a waste of time to have to keep manually re-sizing things because the application doesn't remember the settings.