apparently this is a Window focus problem. The data viewer is not focused when clicking in the white are. However if you click on the titlebar, the data viewer window is focused and you can again use the delete button to delete entries.
Thank you for your post.
I am able to replicate the problem on both Mac OS X 10.5.8 and Mac OS X 10.6.2.
This is definitely a Window focus issue. Following your exact steps do NOT replicate the problem. It should be modified as follows:
1. Open Manage Scripts
2. Select a Script
3. Open Data Viewer (focus is now on Data Viewer and you are able to delete an entry)
4. Return to the Manage Scripts window. If the Data Viewer is in front of the Manage Scripts window, it will remain in the foreground.
5. Return to the Data Viewer, select the "Watch" tab, and try to delete an entry using the Delete key.
As you have discovered, the delete key does not respond to the Data Viewer until you click on the Title Header.
I have forwarded your post along with my findings to our Development and Software Quality Assurance (Testing) departments for review and confirmation. When more information becomes available to me, I will let you know.