Support completely silent installation

[vslavik]

It should be possible to launch update's installer silently. If the app and the installer support it, download and installation would ideally be done completely within WinSparkle UI.
Will need some custom WinSparkle tag in the appcast to tell it that silent install is supported and what parameters to use when launching it.
This will also need to handle access rights correctly: if the app is installed system-wide, ask for elevation, but don't do it if it's in a location writable by the user.

[tanel]

+1

[zsszatmari]

Started working on this one. More precisely, what I will do is to provide an additional tag in the .xml that will be passed on to the downloaded installer, like "/SILENT".

[zsszatmari]

It does work now, requested pull. Have a nice day!

[vslavik]

It does work now, requested pull.

I’m happy to merge that PR once it’s problems are fixed, but note that it does not fix this issue, not fully: it doesn’t show an UI during the (silent) installation, which would be very confusing (is the app doing something? is it broken? should I re-launch it myself?).

[zsszatmari]

In my opinion it's the job of the updater executable to show a progress indicator of some kind, as only it has proper information about the progress. For example, when passing /SILENT to an InnoSetup generated installer, it still shows a progress bar (as opposed to /VERYSILENT, which does not)

[vslavik]

as opposed to /VERYSILENT, which does not

..and which this ticket is about, as explained in its very description.