showSaveDialog should replace extension when switching filters

[ricardomatias]

This is a common feature seen throughout several editors (gimp, inkscape, etc.), that when the user switches a filter the file path gets updated with the new filtered extension.
This is aimed at singular extensions and should be toggled on through the options object that showSaveDialog accepts. In the end, the method should also return the updated file path.

Example:
If the showSaveDialog is called with the file name hello.foo and then there's a filter for an extension called bar, the dialog should update the file name to hello.bar so the user can get a proper feedback to what type of file is he saving to.

[zcbenz]

Which operating system are you using?

[ricardomatias]

Arch Linux. Should this be already working in other operating systems ?

[zcbenz]

This is a regression on Linux.

[ricardomatias]

I've downloaded 0.37.2 and it still has the same behavior as before. Is this functionality supposed to be working with other OS'es ?

[zcbenz]

I only implemented it on Linux. On other platforms this behavior is not expected in most apps as far as I know.

[bsivanov]

As of now (Electron 7.1.10), the extension chosen in the dialog is still (or again?) not added to the file name on Linux.