diff -NaurZ deja-dup-36.3/deja-dup/AssistantOperation.vala deja-dup-36.3-scrollfix/deja-dup/AssistantOperation.vala
--- deja-dup-36.3/deja-dup/AssistantOperation.vala	2017-10-20 22:27:02.000000000 +0200
+++ deja-dup-36.3-scrollfix/deja-dup/AssistantOperation.vala	2018-02-04 10:41:48.892127000 +0100
@@ -89,6 +89,8 @@
   int saved_x;
   int saved_y;
 
+  bool adjustment_at_end;
+
   construct
   {
     add_custom_config_pages();
@@ -168,7 +170,6 @@
 
     string log_line = prefix + " " + file.get_parse_name();
 
-    bool adjustment_at_end = false;
     Gtk.Adjustment adjust = progress_scroll.get_vadjustment();
     if (adjust.value >= adjust.upper - adjust.page_size ||
         adjust.page_size == 0 || // means never been set, means not realized
@@ -178,19 +179,10 @@
     var buffer = progress_text.buffer;
     if (buffer.get_char_count() > 0)
       log_line = "\n" + log_line;
-    if (buffer.get_line_count() >= 100 && adjustment_at_end) {
-      // If we're watching text scroll by, save memory by only keeping last 100 lines
-      Gtk.TextIter start, line100;
-      buffer.get_start_iter(out start);
-      buffer.get_iter_at_line(out line100, buffer.get_line_count() - 100);
-      buffer.delete(ref start, ref line100);
-    }
     
     Gtk.TextIter iter;
     buffer.get_end_iter(out iter);
     buffer.insert_text(ref iter, log_line, (int)log_line.length);
-    if (adjustment_at_end)
-      adjust.value = adjust.upper;
   }
   
   protected void set_secondary_label(string text)
@@ -203,6 +195,25 @@
       secondary_label.hide();
   }
 
+  void update_autoscroll()
+  {
+    if( adjustment_at_end )
+    {
+        Gtk.Adjustment adjust = progress_scroll.get_vadjustment();
+        adjust.value = adjust.upper - adjust.page_size;
+    }
+  }
+
+  bool stop_autoscroll()
+  {
+    Gtk.Adjustment adjust = progress_scroll.get_vadjustment();
+
+    if (adjust.value < adjust.upper - adjust.page_size )
+      adjustment_at_end = false;
+
+    return false;
+  }
+
   protected virtual Gtk.Widget make_progress_page()
   {
     var page = new Gtk.Grid();
@@ -238,7 +249,11 @@
 
     progress_text = new Gtk.TextView();
     progress_text.editable = false;
+    progress_text.size_allocate.connect( update_autoscroll );
     progress_scroll = new Gtk.ScrolledWindow(null, null);
+    progress_scroll.scroll_event.connect( stop_autoscroll );
+    progress_scroll.expand = true;
+    ((Gtk.Range)progress_scroll.get_vscrollbar()).change_value.connect( stop_autoscroll );
     progress_scroll.child = progress_text;
     progress_scroll.hscrollbar_policy = Gtk.PolicyType.AUTOMATIC;
     progress_scroll.vscrollbar_policy = Gtk.PolicyType.AUTOMATIC;