Switch to OOP style code

src/windows/renderer.cc

@@ -0,0 +1,23 @@
+#include "main.h"
+#include "windows/decl.h"
+
+TileRoot root_tile;
+std::vector<std::unique_ptr<TileRoot>> popups;
+Window *focused_window;
+
+void render() {
+  ui::bar.render(new_screen);
+  root_tile.render(new_screen);
+  for (auto &popup : popups)
+    popup->render(new_screen);
+}
+
+void handle_click(KeyEvent event) {
+  for (auto &popup : popups) {
+    if (popup->inside(event.mouse_x, event.mouse_y)) {
+      popup->handle_click(event);
+      return;
+    }
+  }
+  root_tile.handle_click(event);
+}