Initial bug report - http://javafx-jira.kenai.com/browse/RT-24475:

-------------------------------------------------------------
When I overwrite a file using the FileSaveService API there are multiple warning messages:
1.) the FileChooser warns me that an exising file is going to be overwritten, which is fine
2.) as soon as I hit ok I receive a second warning message(JavaFX style) with a broken message(see the screenshot)
-------------------------------------------------------------

First confirmation dialog is native dialog (Glass makes sure that native dialogs are shown - see RT-15422 and RT-24904)
Second confirmation dialog is Java dialog.

Second dialogs are critical for JRE scenarios as JFileChooser doesn't display any confirmation dialog but we shouldn't popup the second dialog for FX scenarios as Glass provides native confirmation dialogs.