This is the old Message Plugin, made compatible for MediaPortal 1.2 and up.
The plugin was originally developed by and-81. All credits go to him, I only added some lines to make it compatible :)
This is a "virtual remote" plugin, which is usefull when you use EventGhost, Girder or some comparable application, which can be used to let the application send button presses to MediaPortal. Use it when MediaPortal does not recognize button presses from your remote and EventGhost or Girder does.
I also added sources for this page.
I now understand why you got that file without the cursor keys.. It was in the sources zip. I updated the sources zip with the correct file :)