fix the way tabs are used

The previous code just assumed a tab was 4 spaces wide.
This is not true, because a tab can be between 1 and 4 spaces wide.

bigtext.py

@@ -3,7 +3,7 @@ import sys
 import math
 import os
 import time
-from typing import Callable
+from typing import Callable, List
 from PyQt6 import QtGui
 
 from PyQt6.QtCore import *
@@ -17,6 +17,7 @@ from conversion import humanbytes
 from highlight_selection import HighlightSelection
 from highlighted_range import HighlightedRange
 from highlightingdialog import HighlightingDialog
+from line import Line
 from logFileModel import LogFileModel
 
 
@@ -126,7 +127,7 @@ class InnerBigText(QWidget):
         self.customContextMenuRequested.connect(self._open_menu)
 
         self.update_font_metrics(QPainter(self))
-        self.lines = []
+        self.lines = List[Line]
         self.selection_highlight = HighlightSelection()
         self._last_double_click_time = 0
         self._last_double_click_line_number = -1
@@ -213,7 +214,7 @@ class InnerBigText(QWidget):
             # triple click: select line
             line_number = self.y_pos_to_line(e.pos().y())
             if line_number == self._last_double_click_line_number and line_number < len(self.lines):
-                line = self.lines[line_number]
+                line: Line = self.lines[line_number]
                 self.selection_highlight.set_start(line.byte_offset())
                 self.selection_highlight.set_end_byte(line.byte_end())
                 self.update()
@@ -227,7 +228,7 @@ class InnerBigText(QWidget):
 
             line_number = self.y_pos_to_line(e.pos().y())
             if line_number < len(self.lines):
-                line = self.lines[line_number]
+                line: Line = self.lines[line_number]
                 for listener in self.line_click_listeners:
                     listener(line.byte_offset())
 
@@ -303,11 +304,11 @@ class InnerBigText(QWidget):
         line_number = self.y_pos_to_line(e.pos().y())
 
         if line_number < len(self.lines):
-            line = self.lines[line_number]
+            line: 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())  # x was behind the last column of this line
+            column_in_line = min(column_in_line, line.length_in_columns())  # x was behind the last column of this line
             char_in_line = line.column_to_char(column_in_line)
-            # print("%s in line %s lcolumn_in_line=%s" % (char_in_line, line_number, column_in_line))
+            print("%s in line %s lcolumn_in_line=%s" % (char_in_line, line_number, column_in_line))
             byte_in_line = line.char_index_to_byte(char_in_line)
             current_byte = line.byte_offset() + byte_in_line
             # print("%s + %s = %s" % (line.byte_offset(), char_in_line, current_byte))
@@ -414,7 +415,7 @@ class InnerBigText(QWidget):
         left_offset = int(-1 * self._left_offset * self.char_width)
         y_line_offset = self.char_height;
         for l in self.lines:
-            text = l.line()  # .replace("\t", tab_string)
+            text = l.line_tabs_replaced()
             painter.drawText(left_offset, y_line_offset, text)
             y_line_offset = y_line_offset + self.char_height