sani haq

same issue > [ERROR:flutter/lib/ui/ui_dart_state.cc(198)] Unhandled Exception: MissingPluginException(No implementation found for method createSubWindow on channel window_manager)

it's a workaround - copy window_caption and customize as needed. use the customize window_caption instead of default one. > window_manager\lib\src\widgets\window_caption.dart

Does not work with i3wm