desktop: Allow only one file picker open at a time

desktop/src/gui/picker.rs

@@ -1,7 +1,10 @@
 use rfd::AsyncFileDialog;
 use std::{
     path::PathBuf,
-    sync::{Arc, Weak},
+    sync::{
+        atomic::{AtomicBool, Ordering},
+        Arc, Weak,
+    },
 };
 use winit::window::Window;
 
@@ -12,16 +15,25 @@ pub struct FilePicker {
 
 struct FilePickerData {
     parent: Weak<Window>,
+    picking: AtomicBool,
 }
 
 impl FilePicker {
     pub fn new(parent: Weak<Window>) -> Self {
         Self {
-            data: Arc::new(FilePickerData { parent }),
+            data: Arc::new(FilePickerData {
+                parent,
+                picking: AtomicBool::new(false),
+            }),
         }
     }
 
     pub async fn pick_file(&self, dir: Option<PathBuf>) -> Option<PathBuf> {
+        if self.data.picking.swap(true, Ordering::SeqCst) {
+            // Already picking
+            return None;
+        }
+
         let mut dialog = AsyncFileDialog::new()
             .add_filter("Flash Files", &["swf", "spl", "ruf"])
             .add_filter("All Files", &["*"])
@@ -35,6 +47,8 @@ impl FilePicker {
             dialog = dialog.set_parent(&parent);
         }
 
-        dialog.pick_file().await.map(|h| h.into())
+        let result = dialog.pick_file().await.map(|h| h.into());
+        self.data.picking.store(false, Ordering::SeqCst);
+        result
     }
 }