QFileDialog::getSaveFileName() -- tie default suffix to selected filter

Quick feature request – when I'm using a file dialog created by getSaveFileName(), and I have a name filter selected (e.g. "*.jpg"), and I type in a file name with no extension, it would be nice if the file name returned by the function had the suffix appended.

If it would be too much of a change to make this the default, maybe it could be a new option in QFileDialog::Options?

This function is being used in my app to save an image, and I use the file extension supplied by the user to determine the image format. If the user has already picked a specific extension from the filter dropdown, it'd be nice if they didn't have to type it in as well.