Support for vte >= 0.52.
See https://bugs.launchpad.net/ubuntu/+source/laditools/+bug/1669111.

--- a/ladi-system-log	2015-09-13 23:38:51.000000000 +0200
+++ b/ladi-system-log	2018-10-17 18:04:59.687899590 +0200
@@ -190,13 +190,13 @@
 
     def on_clear_text (self, data=None):
         current_view = self.logview_notebook.get_current_page ()
-        self.log_files[current_view]["term"].feed ("\033[2J\033[;f", -1)
+        self.log_files[current_view]["term"].feed ("\033[2J\033[;f")
 
     def on_purge (self, data=None):
         current_view = self.logview_notebook.get_current_page ()
         # Opens the file in write anew mode thus clearing the file and close it right away
         open (self.log_files[current_view]['logfile_path'], "w+")
-        self.log_files[current_view]["term"].feed ("\033[2J\033[;f", -1)
+        self.log_files[current_view]["term"].feed ("\033[2J\033[;f")
 
     def run (self):
         self.ui.show_all()