macOS: Reduce save dialog extension filters to their last component

NSSavePanel does not deal well with multi-part extensions, to the point
where it will fail to open if that's the only acceptable extension.

We follow Chromium's lead here and reduce the extension to its last
component, which enables selecting and saving files such as 'foo.tar.gz'.

To improve the user experience we always show file extensions when we
detect a multi-part extension. This makes it clearer what the final
extension will be, and avoids confusing macOS about the intention of
the user when choosing a file that without the final extension also
matches another known extension.

Fixes: QTBUG-38303
Fixes: QTBUG-44227
Change-Id: Id0cee84f758c2cd59fcf1b339caa30f7da07dd1e
Reviewed-by: Timur Pocheptsov <timur.pocheptsov@qt.io>

0 files changed, 0 insertions, 0 deletions