No Direct communication between Dialog API popup window and document
Today there is no support for Direct communication between Dialog API popup window and document. As a work around we are sending commands to the Task Pane first then updating the document. Please add support for communication between dialog API and Popup window
Steve Garland commented
Consider trying to use the full width of the screen for a large display, for example, of a long formula obtained from a cell in Excel. That cannot be done in a task pane, which has an unreasonably small limit on its width. Nor can it be done in a dialog box because the box has no way to obtain information from the document.
Daniel G Wilson commented
Do you have a situation where using a task pane is infeasible?