====== Change the default Text Editor in Xubuntu ======
usually when you want to use another application as a default editor / viewer for some file type you simply install the application you want and when opening the file you right click on the file, select open with other application and choose the new application. check the "Use as default for this kind of file" checkmark and you are don. 

however, some applications like the text editor open a number of different files so it would be a bit of a long lasting job finding all of them and changing the text editor for every file. luckily, we are linux users who know that almost every setting of our systems can be customized in a textfile somewhere. only, where is this text file? 

the textfile containing the global information which application is used to open which file in Xubuntu is located in <code>/usr/share/xubuntu/applications/defaults.list</code> 

so in order to switch from leafpad to gedit, simply <code>apt-get install gedit</code> and then edit the above file <code>sudo gedit /usr/share/xubuntu/applications/defaults.list</code> and replace all occurences of "leafpad" with "gedit" and you are done. 

===== change the default text editor on a per-user-basis =====
now since choosing the text editor is a religious thing among linux users, you might want to do this change for your own user only. if that is the case, copy all lines containing leafpad from the <code>/usr/share/xubuntu/applications/defaults.list</code> file to a file called <code>.local/share/applications/mimeapps.list</code> and change those lines to your liking