At the moment all the 'Local customization' textarea box has been set to a fixed length (4em) which only shows 3 rows no matter how long the text in the 'Standard text' column is.
My suggesting fix is to increase the length of the textarea box if the lenght of the standard text is over 200 characters including the white space.
For example, if the standard text is 410 character, the textarea box will be set to 8em (2 times standard length).
If the standard text is 710 character, the textarea box will be set to 12em (3 times standard length).
If thestandard text is 50 characters (less than 200 characters), it will use the default lenght 4em.
I have tested it in various resultions such as 800X600, 1024x768 and 1280X1024 and they all looks reasonable well.
I have attached 3 screen shots taken in the above resultions.
By the way, I also fixed the validating errors of this page by adding the cols and rows attributes to the textarea box.
The patch for the fix code is also attached.