Looking at an item in mediaviewer.php, I clicked the edit pencil under the word "Filename" (which actually introduces path/name/format/title).
In the edit_interface.php popup, the filename and title boxes were much too short for their contents. In the CSS, I noticed that the filename and date had the same attributes but if title width was defined, I couldn't find it. I removed the file from the date, and added
Code:
#edit_interface-page input[type="text"][id$="FILE"],
#edit_interface-page input[type="text"][id$="TITL"]
{
width:300px
}
That might be a little too wide, but for me it was close enough and I left it like that.