add Tkinter dependency, fix #70

README.md

@@ -26,12 +26,13 @@ A [short *how to* video](https://www.youtube.com/watch/kMsRn38TOiQ) introduces t
 
 [![Scribus Generator how to - high quality pdf generation](pic/screencast.png)](https://www.youtube.com/watch/kMsRn38TOiQ)
 
-
+How to install Scribus Generator ?
 
 [Download](https://github.com/berteh/ScribusGenerator/archive/master.zip) the script and uncompress it anywhere on the local machine. It can be placed with the standard extension scripts. On Windows platform this location would be ``SCRIBUS_INSTALL_DIRECTORY\share\scripts\``, on Ubuntu ``/usr/share/scribus/scripts/``.
 
 **Scribus Generator** can then be started by choosing the script (``ScribusGenerator.py``) within the dialog: _«Scribus → Script → Execute Script»_, or from the [command line](#running-scribus-generator-from-the-command-line).
 
+The graphical interface of Scribus Generator requires Tkinter to be installed in your Python setup. There is no extra dependency to run it from the [command line](#running-scribus-generator-from-the-command-line).
 
 
 What about Scribus?