Do you mean the Find Symbol window filled with lines of a tag file generated by Ctags?
Is only the absolute filename truncated and the rest of the line visible after scrolling with the horziontal scroll bar to right?
I only have short paths and names and so could not check this.
First you can write to IDM support and ask for an increased field width.
Second you can maybe use relative paths instead of the absolute path. If you have specified in your UE/UES project a project directory, this will also work. The only problem with relative paths is, that the list file temporarily generated by UltraEdit - parameter -L %fi in the Ctags options - contains always the project files with full path.
So you have to either replace %fi with a list file generated by yourself or open the tag file after updating and remove the project path from all lines in the tag file. The first one is not practicable if the list of project files often changes except you use a macro to generate the list file. The second one is also annoying if you often update the tag file.
To create a tag file with relative paths you could also replace the -L %fi ctags option with your own options for example with --exclude=[pattern] and --recurse=yes and the working directory is set to the project directory. See the manual of ctags for details.