This Power Tool is a Visual Studio add-in that provides an easy way to parse and edit Open Packaging Conventions files, including Word, Excel and PowerPoint documents.
In VS 2019, double-clicking a Word file in a project opens the Package File editor even if it's not the default editor. To reproduce, right-click a Word document and select Open With.... Then select Word in the list and click the Set as Default button. Then click OK. Double-click a Word document and see that it's opened not in Word, but in the Package File editor. This worked correctly in VS 2017
In VS 2019, double-clicking a Word file in a project opens the Package File editor even if it's not the default editor. To reproduce, right-click a Word document and select Open With.... Then select Word in the list and click the Set as Default button. Then click OK. Double-click a Word document and see that it's opened not in Word, but in the Package File editor. This worked correctly in VS 2017