window: Use path instead of URI for "Open With"

Fixes an issue where paths with spaces or anything
else encoded within the URI could not be opened
externally.

src/widgets/image_view.rs

@@ -371,7 +371,7 @@ impl LpImageView {
         Ok(())
     }
 
-    fn current_page(&self) -> Option<LpImagePage> {
+    pub fn current_page(&self) -> Option<LpImagePage> {
         let carousel = &self.imp().carousel;
         let pos = carousel.position().round() as u32;
         if carousel.n_pages() > 0 {