fix: use GTK3 backend for Linux file dialogs

Avoid ashpd/xdg-portal compilation issues on Linux CI

Author: m_igashi

.github/workflows/release.yml

@@ -80,7 +80,7 @@ jobs:
         if: runner.os == 'Linux'
         run: |
           sudo apt-get update
-          sudo apt-get install -y libxkbcommon-dev libwayland-dev
+          sudo apt-get install -y libxkbcommon-dev libwayland-dev libgtk-3-dev
 
       - name: Build GUI
         run: cargo build --release --manifest-path mp3rgui/Cargo.toml --target ${{ matrix.target }}

mp3rgui/Cargo.toml

@@ -11,10 +11,17 @@ repository = "https://github.com/M-Igashi/mp3rgain"
 eframe = "0.31"
 egui = "0.31"
 egui_extras = { version = "0.31", features = ["all_loaders"] }
-rfd = "0.15"
 image = { version = "0.25", default-features = false, features = ["png"] }
 mp3rgain = { path = ".." }
 
+# Linux: use GTK3 backend to avoid ashpd/xdg-portal compilation issues
+[target.'cfg(target_os = "linux")'.dependencies]
+rfd = { version = "0.15", default-features = false, features = ["gtk3"] }
+
+# macOS/Windows: use native file dialogs
+[target.'cfg(not(target_os = "linux"))'.dependencies]
+rfd = "0.15"
+
 [target.'cfg(windows)'.build-dependencies]
 winresource = "0.1"