3 files changed, 22 insertions, 5 deletions
diff --git a/ext/fg/js/frontend-api-sender.js b/ext/fg/js/frontend-api-sender.js
index a1cb02c4..2e037e62 100644
--- a/ext/fg/js/frontend-api-sender.js
+++ b/ext/fg/js/frontend-api-sender.js
@@ -26,9 +26,7 @@ class FrontendApiSender {
         this.disconnected = false;
         this.nextId = 0;
 
-        this.port = chrome.runtime.connect(null, {name: 'backend-api-forwarder'});
-        this.port.onDisconnect.addListener(this.onDisconnect.bind(this));
-        this.port.onMessage.addListener(this.onMessage.bind(this));
+        this.port = null;
     }
 
     invoke(action, params, target) {
@@ -36,6 +34,10 @@ class FrontendApiSender {
             return Promise.reject('Disconnected');
         }
 
+        if (this.port === null) {
+            this.createPort();
+        }
+
         const id = `${this.nextId}`;
         ++this.nextId;
 
@@ -48,6 +50,12 @@ class FrontendApiSender {
         });
     }
 
+    createPort() {
+        this.port = chrome.runtime.connect(null, {name: 'backend-api-forwarder'});
+        this.port.onDisconnect.addListener(this.onDisconnect.bind(this));
+        this.port.onMessage.addListener(this.onMessage.bind(this));
+    }
+
     onMessage({type, id, data, senderId}) {
         if (senderId !== this.senderId) { return; }
         switch (type) {
diff --git a/ext/fg/js/popup-proxy-host.js b/ext/fg/js/popup-proxy-host.js
index 041900ed..1f14a06f 100644
--- a/ext/fg/js/popup-proxy-host.js
+++ b/ext/fg/js/popup-proxy-host.js
@@ -116,12 +116,14 @@ class PopupProxyHost {
     async termsShow(id, elementRect, writingMode, definitions, options, context) {
         const popup = this.getPopup(id);
         elementRect = this.jsonRectToDOMRect(popup, elementRect);
+        if (!PopupProxyHost.popupCanShow(popup)) { return false; }
         return await popup.termsShow(elementRect, writingMode, definitions, options, context);
     }
 
     async kanjiShow(id, elementRect, writingMode, definitions, options, context) {
         const popup = this.getPopup(id);
         elementRect = this.jsonRectToDOMRect(popup, elementRect);
+        if (!PopupProxyHost.popupCanShow(popup)) { return false; }
         return await popup.kanjiShow(elementRect, writingMode, definitions, options, context);
     }
 
@@ -129,6 +131,10 @@ class PopupProxyHost {
         const popup = this.getPopup(id);
         return popup.clearAutoPlayTimer();
     }
+
+    static popupCanShow(popup) {
+        return popup.parent === null || popup.parent.isVisible();
+    }
 }
 
 PopupProxyHost.instance = PopupProxyHost.create();
diff --git a/ext/fg/js/popup.js b/ext/fg/js/popup.js
index 1b15977b..08c4bfcb 100644
--- a/ext/fg/js/popup.js
+++ b/ext/fg/js/popup.js
@@ -239,9 +239,12 @@ class Popup {
     }
 
     focusParent() {
-        if (this.parent && this.parent.container) {
+        if (this.parent !== null) {
             // Chrome doesn't like focusing iframe without contentWindow.
-            this.parent.container.contentWindow.focus();
+            const contentWindow = this.parent.container.contentWindow;
+            if (contentWindow !== null) {
+                contentWindow.focus();
+            }
         } else {
             // Firefox doesn't like focusing window without first blurring the iframe.
             // this.container.contentWindow.blur() doesn't work on Firefox for some reason.