oscommerce search box modification

I have a modified search box which allows the customer to search within categories and manufacturers, but the only trouble is the length of the box. If you have a long category name, the box, and therefore the column expands to reflect this. What I want is some control over the size of the box, like the manufacturers box has. I know this is set up on the configuration table on the database using MAX_DISPLAY_MANUFACTURER_NAME_LEN, and so I would like the search box to do the same. To see what I mean, visit [login to view URL] and take a look at the search box. I have also uploaded the search box and manufacturers box so you can see the code. Like my last project, I'm sure there is such a simple solution but I'm not confidient enough to mess with the php and I need it done fairly quickly. Thanks