Extender is part of video 4 in the series I'm watching on YouTube. I've not go that far as I wanted to experiment with Flirc first. I think maybe it would be useful for me to have a wireless keyboard or IR keyboard of some kind with alphabet keys. At the moment I have set some useful general functions (tab, space, backspace, delete). I also set some media keys but they only seem to work with certain video playback software and don't work well in other Apps. I think I need to experiment really and find what works for me. At least I can now do some further customisation and assign keys I need. Perhaps I can map alt and ctrl functions to unused keys. I'm mapping general functions to number keys because I don't have a lot of spare buttons on the remote. I'm also not sure if it's better to map left / right / up / down or page up / page down which I currently map separately. I also use rewind and fast forward but might be better with previous and next track. I would like to use Kodi more but the Netflix Addon doesn't work too well with it, it basically just launches a separate Chrome process in a new window and puts it in Kiosk mode so it seems like it's running in Kodi. I use Google Play for Movies, TV and Music but these don't map well with Kodi so far.
UPDATE
I can see better how this works now, I was able to map Alt + F1 to key 5 for menu in my window manager, so I can now access my applications - e.g. Flirc config, Kodi, Firefox, Chrome, VLC etc. I also mapped Alt + Tab to key 6 and Ctrl + Q to key 9.
So now I have:
1: Tab, 2: Space, 3: Delete, 4: Backspace, 5: XFCE Menu, 6: Switch Application, 7: Page Up, 8: Page Down, 9: Close Window.
However Alt + Tab key doesn't work well because short press switches to next or previous App and long press cycles very fast through all Apps. Maybe this can be slowed down somehow.