On Windows 10 64-bit 1709, Firefox 57.0.4 this add-on does not work. When I right-click on the selected text and chose "Save text to file" all I get is a pop-up that informs me that text has been saved. Where??? In the add-on preferences i have checked "Show directory selection dialog", but this option does not work. I do not get directory selection, just a fake pop-pup. The file is not getting saved in Downloads directory in Windows 10 as a picture shows. It is going to never-never, if at all.

Update: to make it work I had choose "Uniquify" in the "If file exists" dropdown dialog box. Now it does exactly as it says. Thanks.