I think one issue here is that this case in

if (index == selectables.length - 1 && lastSelectionResult == SelectionResult.next) {
  return SelectionResult.next;
}

if (lastSelectionResult == SelectionResult.next) {
  continue;
}
.
.
.

I haven't been able to find the root cause of this yet. The M3 Typography does set the height for TextStyle to 1.43 for bodyMedium which brings the issue to the surface. However, I think the issue being observed was also present before using useMaterial3: true.

If I try, and resize the window (I tried making it smaller). I am also not able to select the final Hello, world.

import 'package:flutter/material.dart';

void main() {
  runApp(const MainApp());
}

class MainApp extends StatelessWidget {
  const MainApp({super.key});

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      // theme: ThemeData.light(useMaterial3: true),
      home: Scaffold(
        body: SafeArea(
          child: Center(
            child: SelectionArea(
              child: Text.rich(
                  const TextSpan(
                      children: <InlineSpan>[
                        TextSpan(
                          text:
                              'Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua.',
                        ),
                        WidgetSpan(child: Text('Some text in a WidgetSpan. ')),
                        TextSpan(text: 'Hello, world.'),
                      ],
                  ),
              ),
            ),
          ),
        ),
      ),
    );
  }
}

I think we can do two things in this situation if we cannot find and fix the root cause in time.

1. Merge this PR with the workaround and leave a TODO along with a link to the issue describing the problem.
2. Merge this PR but instead of the workaround just skip the test in question and leave a TODO with an issue linked.

(Triage): @bleroux Do you still have plans to follow up on the feedback given above?

(Triage): @bleroux Do you still have plans to follow up on the feedback given above?

Yes, I will soon update this PR as proposed in #129627 (comment).
The first step will be to file a more detailed issue that will be linked from a TODO in the updated PR.

@Renzo-Olivares , revisiting this, I wonder if the issue is only related to how the test is written.
Using a golden image we can have a better understanding of what happens.

The test simulates a right click on the word ‘Hello,’.

• To get the click position the test relies on the textOffsetToPosition helper function which relies on Paragraph.getOffsetForCaret.
• Paragraph.getOffsetForCaret returns the offset at the top left of a glyph (which means above the vertical space induced by the line height).
• So the position used to simulate the click is not on the text but above it.
• MultiSelectableSelectionContainerDelegate.handleSelectWorld relies on selectable fragments bounds to check if the mouse event position is inside the bounds of one of the selectable fragments. But the bounds of those fragments are the ones around the text (line height induced vertical spaces are not part of those bounds).

So my question for you is “‘should MultiSelectableSelectionContainerDelegate allow selection above and below the text when lineHeight is set?”.
If the answer is no, the test should adjust the gesture vertical offset.

Hey @bleroux, just checking in from triage, what's the status of this PR?

Hi @bleroux I apologize for missing this. Thank you for the clear and in depth explanation of the issue.

From my observation on the web you can select between above and below the lineHeight set. It looks like it will always select the first word of the paragraph in this case. The current implementation of handleSelectWord in MultiSelectableSelectionContainerDelegate does not allow for this because it checks if the position is within the text rect. I think for now we can adjust the gesture vertical offset and fix the assertion crash https://github.com/flutter/flutter/pull/129627#issuecomment-1609958996, but we should also add a TODO and create an issue for this so we can get this behavior right in the future.

Hey @Renzo-Olivares!
I filed #133637 and I updated the PR:

• add a TODO pointing to this issue.
• make the change you proposed in Update SelectableRegion test for M3 #129627 (comment)