Fix: menu positioning in CupertinoNavigationBar on Flutter 3.35.x - #76

Summary

Fixes menu positioning and animation issues when PullDownButton is used in CupertinoNavigationBar's trailing widget on Flutter 3.35.0+.

Fixes #74

Videos

Root Cause

Flutter 3.35.0 introduced a regression (via PR flutter/flutter#168866) where CupertinoNavigationBar wraps its children (leading, middle, trailing) with a new MediaQueryData that only sets the textScaler field:

// Broken in Flutter 3.35.0
MediaQuery(
  data: MediaQueryData(textScaler: ...),  // All other fields default!
  child: userTrailing,
)

This causes all other MediaQueryData fields to reset to defaults:

• size → Size(0, 0)
• padding → EdgeInsets.zero
• devicePixelRatio → 1.0

PullDownButton's positioning logic relies on MediaQuery.of(context).size to calculate screen bounds, which now returns invalid dimensions when the button is inside CupertinoNavigationBar's trailing widget.

Solution

Pass the navigator overlay's context for MediaQuery lookups instead of using the button's context. The overlay always has complete MediaQueryData with correct screen dimensions.

Changes:

• Add optional mediaQueryContext parameter to getRect() in extensions.dart
• Add optional overlayContext parameter to animationAlignment() in route.dart
• Update both call sites in pull_down_button.dart to pass navigator.overlay!.context