init browser modules

src/app/browser.rs

@@ -0,0 +1,15 @@
+#[path = "browser/header.rs"] mod header;
+#[path = "browser/main.rs"] mod main;
+
+use gtk4 as gtk;
+use gtk::{Application, ApplicationWindow};
+
+pub fn new(app: &Application) -> ApplicationWindow
+{
+    return ApplicationWindow::builder().application(app)
+                                       .default_width(640)
+                                       .default_height(480)
+                                     //.titlebar(&header::new())
+                                       .child(&main::new())
+                                       .build();
+}