If you don't like to use XIDE's internal editor for some filetypes, you can attribute an external editor.
Simply edit the
XIDE.cfg file in your main XIDE folder, and add entries in the
[FileTools] section. If this section does not exist, add it.
[FileTools] xml = notepad.exe txt = wordpad.exe,%1
The 2nd syntax allows you to use command line options, for example
wordpad.exe , /param1 %1 /param2
(%1 is replaced with the filename)
If you press CTRL or SHIFT while opening a file, it gets opened inside XIDE, instead of the tool you specified.