The extension filter needs an improvement...it does not act as a filter at the moment
 
1.) It does not filter the contents of the current folder depending on the current filetype
 Usually when a png filter is specified (there's a "[png]" value in the "Save as type" box) I would expect to see all png files in the current folder(this is the defaul behavior in windows)
 
2.) the extension is not appended to the filename:
If a png filter is specified as a filetype, then when the user inputs "name" and clicks Save, a "name.png" file should be created, but not a file "name"
 
3.) the suggested filename is always ignored...what's the point in having a suggested name argument then?
 fileSaveService.saveFileDialog(null, supportedImageExportExtensions, imageInputStream, "my_suggested_name.png");//always ignored