fix: Use libportal to open script files

There's a bug in GLib that makes Text Pieces to open script files
in Text Pieces itself:
https://gitlab.gnome.org/GNOME/glib/-/issues/2851

I fixed it by using `libportal`'s `Xdp.Portal.open_uri` instead of
`gtk4`'s `Gtk.show_uri`.

Fixes liferooter#118

build-aux/flatpak/com.github.liferooter.textpieces.yaml

@@ -31,13 +31,6 @@ cleanup:
 
 modules:
 
-- name: blueprint
-  buildsystem: meson
-  sources:
-  - type: git
-    url: https://gitlab.gnome.org/jwestman/blueprint-compiler
-    branch: main
-
 - name: textpieces
   builddir: true
   buildsystem: meson
@@ -46,6 +39,13 @@ modules:
     path: ../..
 
   modules:
+  - name: blueprint
+    buildsystem: meson
+    sources:
+    - type: git
+      url: https://gitlab.gnome.org/jwestman/blueprint-compiler
+      branch: main
+
   - name: python3-pyyaml
     buildsystem: simple
     build-commands:
@@ -55,3 +55,16 @@ modules:
     - type: file
       url: https://files.pythonhosted.org/packages/36/2b/61d51a2c4f25ef062ae3f74576b01638bebad5e045f747ff12643df63844/PyYAML-6.0.tar.gz
       sha256: 68fb519c14306fec9720a2a5b45bc9f0c8d1b9c72adf45c37baedfcd949c35a2
+
+  - name: libportal
+    buildsystem: meson
+    config-opts:
+    - -Dbackend-gtk3=disabled
+    - -Dbackend-gtk4=enabled
+    - -Dbackend-qt5=disabled
+    - -Ddocs=false
+    - -Dtests=false
+    sources:
+    - type: git
+      url: https://github.com/flatpak/libportal
+      tag: main

meson.build

@@ -91,6 +91,8 @@ textpieces_deps = [
   dependency('gio-unix-2.0', version: '>= 2.50'),
   dependency('gtk4', version: '>= 4.2'),
   dependency('gee-0.8', version: '>= 0.8'),
+  dependency('libportal', version: '>= 0.6'),
+  dependency('libportal-gtk4', version: '>= 0.6'),
   json_glib_dep,
   gtksourceview_dep,
   libadwaita_dep,

src/tools/Tool.vala

@@ -169,12 +169,13 @@ namespace TextPieces {
          */
         public void open (Gtk.Window? window)
                 requires (!this.is_system) {
-            Gtk.show_uri (
-                window,
+            new Xdp.Portal ().open_uri.begin (
+                Xdp.parent_new_gtk(window),
                 File.new_build_filename (
                     Tool.CUSTOM_TOOLS_DIR.get (), this.script
                 ).get_uri (),
-                Gdk.CURRENT_TIME
+                ASK | WRITABLE,
+                null
             );
         }