fence focus inside modals

copyparty/web/browser.css

@@ -1013,6 +1013,8 @@ html.light #rui {
 #barpos,
 #u2conf label,
 #rui label,
+#modal-ok,
+#modal-ng,
 #ops {
 	-webkit-user-select: none;
 	-moz-user-select: none;

copyparty/web/util.js

@@ -725,11 +725,15 @@ var modal = (function () {
         a.onclick = ok;
 
         (ebi('modali') || a).focus();
+        document.addEventListener('focus', onfocus);
+        timer.add(onfocus);
     };
 
     r.hide = function () {
-        o.parentNode.removeChild(o);
+        timer.rm(onfocus);
+        document.removeEventListener('focus', onfocus);
         document.removeEventListener('keydown', onkey);
+        o.parentNode.removeChild(o);
         r.busy = false;
         setTimeout(next, 50);
     };
@@ -748,6 +752,17 @@ var modal = (function () {
             cb_ng(null);
     }
 
+    function onfocus(e) {
+        var ctr = ebi('modalc');
+        if (!ctr || !ctr.contains || !document.activeElement || ctr.contains(document.activeElement))
+            return;
+
+        setTimeout(function () {
+            ebi('modal-ok').focus();
+        }, 20);
+        ev(e);
+    }
+
     function onkey(e) {
         if (e.code == 'Enter') {
             var a = ebi('modal-ng');