simplify cell selection

Author: willmcgugan

src/textual/_compositor.py

@@ -926,12 +926,11 @@ def get_widget_and_offset_at(
         offset_y: int | None = None
         offset_x = 0
         offset_x2 = 0
-        cell_position = 0
 
         from rich.cells import get_character_cell_size
 
         for segment in line:
-            end += len(segment.text)
+            end += segment.cell_length
             style = segment.style
             if style is not None and style._meta is not None:
                 meta = style.meta
@@ -940,25 +939,19 @@ def get_widget_and_offset_at(
                     offset_x2 = offset_x + len(segment.text)
 
                     if x < end and x >= start:
-                        if x == end - 1:
-                            segment_offset = len(segment.text)
-                        else:
-                            segment_cell_length = 0
-                            cell_cut = x - cell_position
-                            segment_offset = 0
-                            for character in segment.text:
-                                if segment_cell_length >= cell_cut:
-                                    break
-                                segment_cell_length += get_character_cell_size(
-                                    character
-                                )
-                                segment_offset += 1
+                        segment_cell_length = 0
+                        cell_cut = x - start
+                        segment_offset = 0
+                        for character in segment.text:
+                            if segment_cell_length >= cell_cut:
+                                break
+                            segment_cell_length += get_character_cell_size(character)
+                            segment_offset += 1
                         return widget, (
                             None
                             if offset_y is None
                             else Offset(offset_x + segment_offset, offset_y)
                         )
-            cell_position += cell_len(segment.text)
             start = end
 
         return widget, (None if offset_y is None else Offset(offset_x2, offset_y))