OfficeJS Add-in Task Pane Width Persistence
When a user resizes the add-in task pane and saves the document, the width of the task pane is stored in the document specifically in /word/webextensions/taskpanes.xml. However, when the document is reopened, and the add-in is reloaded, the officeJS task pane ignores the value of the width attribute stored in the document. The task pane is always displayed with the same fixed size.
It is important for our add-in to maintain its width because of the nature of the content that must be shown in the add-in.
Please see the details in