Match the GTK file filters with the new spec.

CHANGELOG.md

@@ -103,7 +103,7 @@ This means that druid no longer requires cairo on macOS and uses Core Graphics i
 - GTK: Support disabled menu items. ([#897] by [@jneem])
 - X11: Support individual window closing. ([#900] by [@xStrom])
 - X11: Support `Application::quit`. ([#900] by [@xStrom])
-- GTK: Support file filters in open/save dialogs. ([#903] by [@jneem])
+- GTK: Support file filters in open/save dialogs. ([#903] by [@jneem], [#957] by [@xStrom])
 - GTK: Support DPI values other than 96. ([#904] by [@xStrom])
 - Windows: Removed flashes of white background at the edge of the window when resizing. ([#915] by [@xStrom])
 - Windows: Reduced chance of white flash when opening a new window. ([#916] by [@xStrom])
@@ -231,6 +231,7 @@ This means that druid no longer requires cairo on macOS and uses Core Graphics i
 [#951]: https://github.com/xi-editor/druid/pull/951
 [#953]: https://github.com/xi-editor/druid/pull/953
 [#954]: https://github.com/xi-editor/druid/pull/954
+[#957]: https://github.com/xi-editor/druid/pull/957
 [#959]: https://github.com/xi-editor/druid/pull/959
 [#961]: https://github.com/xi-editor/druid/pull/961
 [#963]: https://github.com/xi-editor/druid/pull/963

druid-shell/src/platform/gtk/dialog.rs

@@ -53,7 +53,9 @@ pub(crate) fn get_file_dialog_path(
 
     dialog.set_show_hidden(options.show_hidden);
 
-    dialog.set_select_multiple(options.multi_selection);
+    if action != FileChooserAction::Save {
+        dialog.set_select_multiple(options.multi_selection);
+    }
 
     // Don't set the filters when showing the folder selection dialog,
     // because then folder traversing won't work.
@@ -76,15 +78,9 @@ pub(crate) fn get_file_dialog_path(
             }
         }
 
-        if let Some(default_file_type) = &options.default_type {
-            if options.allowed_types.is_some() && !found_default_filter {
-                // It's ok to set a default file filter without providing a list of
-                // allowed filters, but it's not ok (or at least, doesn't work in gtk)
-                // to provide a default filter that isn't in the (present) list
-                // of allowed filters.
-                log::warn!("default file type not found in allowed types");
-            } else if !found_default_filter {
-                dialog.set_filter(&file_filter(default_file_type));
+        if let Some(dt) = &options.default_type {
+            if !found_default_filter {
+                log::warn!("The default type {:?} is not present in allowed types.", dt);
             }
         }
     }