a few changes to make A/B testing easier

app/dragManager.js

@@ -0,0 +1,24 @@
+export default function(state, emitter) {
+  emitter.on('DOMContentLoaded', () => {
+    document.body.addEventListener('dragover', event => {
+      if (state.route === '/') {
+        event.preventDefault();
+      }
+    });
+    document.body.addEventListener('drop', event => {
+      if (state.route === '/' && !state.transfer) {
+        event.preventDefault();
+        document.querySelector('.upload-window').classList.remove('ondrag');
+        const target = event.dataTransfer;
+        if (target.files.length === 0) {
+          return;
+        }
+        if (target.files.length > 1 || target.files[0].size === 0) {
+          return alert(state.translate('uploadPageMultipleFilesAlert'));
+        }
+        const file = target.files[0];
+        emitter.emit('upload', { file, type: 'drop' });
+      }
+    });
+  });
+}