Liquid XML Studio 2019
User Interface Guide > Options > Environment > Debugger

Max output files to open when 'Execute' completes

Some transforms (XSLT/XQuery/Datamapper) can produce multiple output files, in some cases this may be 100's or 1000's of them. If the editor tried to open them all it would grind to a halt, so if an attempt is made to open more files than this, the user is asked to confirmation.