Currently, using the {{showSaveDialog()}} and {{showOpenDialog()}} methods on the {{FileChooser}}, there is no way to let users _append to_ (an action closer to _saving_ than _opening_) an existing file, without getting a warning like this

{quote}
[specified file in dialog] already exists.
Do you want to replace it?
{quote}

Following my teams format, my story would be:

{quote}
As a developer & user of Apache POI, I want to allow my users to specify an excel workbook that they can append sheets to, so that they update existing workbooks containing like data, keeping their files organized.
{quote}

I would argue that, while not entirely common, selecting a file to be _updated_ as a form of saving is an important feature. Consider a project file that the user is working on: if the user opens the application with that project file, and then selects save, and then selects the file they initially opened with, there's a good chance that technically the file would be replaced, making that dialog technically accurate, but the experience is not one of replacing but rather updating.

Then there's also what I mentioned in my story, which is that we're using Excel Workbook's multiple sheet feature, to allow our users to add our data in the form of multiple sheets to existing workbooks. This makes it quite convenient for our users to keep an excel workbook at parity with the content of our application, as they modify that content.

Worth mentioning is that I feel this is the difference between a RESTful {{put}} and {{post}}, my point being that if this was big enough to make it into the HTTP spec, why not JavaFX?