Thanks for jumping in and submitting a PR for this. Some questions here. I always hesitate to add a new parameter to TextField, so I want to make sure we get it right.

When the user dismisses the modal, we want the focus to go back the text field with the same selection that it had before.

What platform is this on? Is this the same behavior that you would expect if you tab into that field?

Some other possible paths here for completeness:

• Keep the boolean parameter as-is in this PR, but set it to a default value that considers the current platform.
• Somehow give the user more generic control over what happens when the user focuses the field (make the parameter a function instead of a bool?).

@camfrandsen Sorry for the slow response (vacation). Have you had any luck with the function? I'm thinking of something that would completely replace _adjustedSelectionWhenFocused, but that might not be practical since _adjustedSelectionWhenFocused uses private members currently. But would that kind of approach work for your use case or is it not doable?

Otherwise, what if your existing boolean parameter defaulted to something like this?

  static bool get defaultHighlightAllOnFocus {
    if (kIsWeb) {
      return true;
    }
    return switch (defaultTargetPlatform) {
      TargetPlatform.android => false,
      TargetPlatform.iOS => false,
      TargetPlatform.fuchsia => false,
      TargetPlatform.linux => true,
      TargetPlatform.macOS => true,
      TargetPlatform.windows => true,
    };
  }

Then we could remove the line about highlightAllOnFocus only applying to web and desktop? I'm just trying to make sure that this parameter makes sense and doesn't have any strange behavior that's dependent on our current private approach.