Annotation toolbar customisation

[mutumbakato]

ONLY FOR DEMONSTRATION

This is a demonstration of how we can natively customise the annotation toolbar in PSPDFKit for Futter.
For more details on how to customise annotation toolbar natively, please refer to the following links:

• iOS: https://pspdfkit.com/guides/ios/customizing-the-interface/customizing-the-annotation-toolbar/#annotation-buttons
• Android: https://pspdfkit.com/guides/android/customizing-the-interface/customizing-the-toolbar/#change-the-grouping-of-toolbar-items