# Opacity changing is firing unnecessary annotation changed event

**URL:** <https://pdfjs.community/t/opacity-changing-is-firing-unnecessary-annotation-changed-event/849>\
**Category:** Technical Support\
**Created:** [June 25, 2021, 10:34am UTC](https://pdfjs.community/t/opacity-changing-is-firing-unnecessary-annotation-changed-event/849 "2021-06-25T10:34:48Z")\
**Posts on this page:** 1\
**Showing post:** 2

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**Author:** ![system](https://canada1.discourse-cdn.com/flex031/uploads/pdfjscommunity/original/1X/ffbcd25c7d423db8d5acd5db201c272f4db306dd.png) [@system](https://pdfjs.community/u/system)\
**Post date:** [June 25, 2021, 10:34am UTC](https://pdfjs.community/t/opacity-changing-is-firing-unnecessary-annotation-changed-event/849/2 "2021-06-25T10:34:53Z")

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**Hello, I’m Ron, an automated tech support bot 🤖**

While you wait for one of our customer support representatives to get back to you, please check out some of these documentation pages:

Guides:
- [Create fillable forms - Modify fields to readonly](https://pdfjs.express/documentation/forms/fill-form-fields#modify-fields-to-readonly)
- [Customize annotation tools - Event when tool creates an annotation](https://pdfjs.express/documentation/annotation/customizing-tools#event-when-tool-creates-an-annotation)
- [Add annotation events - annotationSelected](https://pdfjs.express/documentation/annotation/annotation-events#annotationselected)

APIs:
- [CoreControls.AnnotationManager - deleteAnnotation(annotation [, options])](https://pdfjs.express/api/CoreControls.AnnotationManager.html#deleteAnnotation__anchor)
- [CoreControls.BlackBoxAnnotationManager - preloadAnnotations(An)](https://pdfjs.express/api/CoreControls.BlackBoxAnnotationManager.html#preloadAnnotations__anchor)
- [CoreControls.AnnotationHistoryManager - historyChanged](https://pdfjs.express/api/CoreControls.AnnotationHistoryManager.html#event:historyChanged__anchor)

Forums:
- [Flipped annotations aren’t triggering annotationChanged (modify) event, also NOT getting saved/export](https://pdfjs.community/t/flipped-annotations-arent-triggering-annotationchanged-modify-event-also-not-getting-saved-export/591/2)
- [Annotations are getting displaced when zoom in and out are done abit fast](https://pdfjs.community/t/annotations-are-getting-displaced-when-zoom-in-and-out-are-done-abit-fast/567/1)
- [Get previous annotation from annotationChanged event](https://pdfjs.community/t/get-previous-annotation-from-annotationchanged-event/700/3)

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_[View the full topic](https://pdfjs.community/t/opacity-changing-is-firing-unnecessary-annotation-changed-event/849)._