FIX/ADD no "Save As.." save folder asked in Save all tabs #directory

[allanlaal]

use case

I open up 100 tabs. I wait them to load I rightclick SingleFile toolbar icon → Save tabs → Save all tabs

expected

it asks what folder to save those tabs into

actual

silently saves them into $HOME

[gildas-lormeau]

Unfortunately, extensions cannot open the "Save as..." dialog to select a folder.

[allanlaal]

damn WebExtensions :(

could it show an Alert with a hint of what and where it was saved? I've seen that in fx plugins