Implement ui_context for Application to support default draggable window

 src/main.rs | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/src/main.rs b/src/main.rs
index 3900578..1fc24f9 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -487,6 +487,10 @@ impl FilesystemApp {
 impl Application for FilesystemApp {
     type Message = Message;
 
+    fn ui_context(&self) -> Option<&cce_ui::context::UiContext> {
+        Some(&self.ui_context)
+    }
+
     fn new(_qh: &QueueHandle<cce_ui::engine::EngineState<Self>>, sender: calloop::channel::Sender<Self::Message>) -> Self {
         // Parse command line arguments
         let args: Vec<String> = std::env::args().collect();