2 files changed, 12 insertions, 1 deletions

diff --git a/index.html b/index.html
index fa1ef21..ddcdbcf 100644
--- a/index.html
+++ b/index.html
@@ -43,7 +43,7 @@
           <code>\setbeameroption{show notes on second screen=right}</code>)
         </p>
 
-        <p class="warning">
+        <p id="warning" class="warning">
           <noscript>A web browser with JavaScript support is required to use this application.</noscript>
         </p>
 
diff --git a/pointless/viewer/init.js b/pointless/viewer/init.js
index a9294ea..cb01fab 100644
--- a/pointless/viewer/init.js
+++ b/pointless/viewer/init.js
@@ -28,8 +28,19 @@ function initCache() {
   offlineCapableIndicator.style.visibility = "visible";
 }
 
+function checkPopupPermission() {
+  try {
+    const popup = window.open();
+    popup.close();
+  } catch(error) {
+    const warningMessage = document.getElementById("warning");
+    warningMessage.textContent = "A pop-up blocker is active. Make sure to allow pop-ups on this website.";
+  }
+}
+
 function init() {
   initCache();
+  checkPopupPermission();
 
   const viewer = new Viewer();