Thank you for your post.
This occurs on Mac OS X 10.5.8, Mac OS X 10.6.4, Windows XP and Windows Vista. After selecting a layout in one window, if you switch to the Inspector window and change the values, your Window focus is now on the Inspector. You will need to click to the Layout window to put focus back on that window.
Please enter this as a suggestion into our Feature Requests web form at:
These suggestions are read by Development and Product Management where they are then discussed and considered for future releases. I could copy your post and paste it into the web form, but there are a couple of questions asked that only you can answer.