Combo box not showing full text of options

Hey everyone, I’m implementing a random header plugin found here:
https://www.martinet.nl/wp-site/random-header-plugin

Comments are closed on that blog, or I would post this there.

In the options page for it, there is a drop-down box that lets you choose from the images in the directory to add to your random images. But the box is shortened, as if there were no options there. There are files in the directory, and you can expand the combo box, and see all the files, only you can only see the first two letters of each of the file names. Here is a screenshot: https://www.packerworld.com/nate_personal/screenshot.jpg

I know basic HTML and some PHP, but can’t find anywhere in the code to fix this. You can see the code right here: https://www.packerworld.com/nate_personal/options.txt

Any ideas to get the combo box to show the full file names?