Configuring Kate

When Kate is already open, and in Firefox I press Ctrl-U to open the web page in the assigned external text editor (Kate), the web content opens in a second Kate session. I want to use the current session only. I'm an MDI kind of person. :) Editing the Firefox preferences to "kate --use" then causes Firefox to open the web page content in the Firefox viewer rather than Kate. All of my kate related *.desktop files are set to kate --use. Any ideas how to fix this? Darrell