fix selection of the suffix of a line

bigtext.py

@@ -284,7 +284,7 @@ class InnerBigText(QWidget):
         if line_number < len(self.lines):
             line = self.lines[line_number]
             column_in_line = self.x_pos_to_column(e.pos().x()) + self._left_offset
-            column_in_line = min(column_in_line, line.length() - 1)  # x was behind the last column of this line
+            column_in_line = min(column_in_line, line.length())  # x was behind the last column of this line
             char_in_line = line.column_to_char(column_in_line)
             # print("%s in line %s" % (char_in_line, line_number))
             byte_in_line = line.char_index_to_byte(char_in_line)