Index: gc_lang/fr/tb/content/editor.js
==================================================================
--- gc_lang/fr/tb/content/editor.js
+++ gc_lang/fr/tb/content/editor.js
@@ -6,10 +6,18 @@
         this.xEditor = GetCurrentEditor();
         this.lNode = [];
         this.lParsableNodes = ["P", "LI"];
         this.lRootNodes = ["DIV", "UL", "OL"];
     };
+
+    _getTextFromNode (xNode) {
+        if ("innerHTML" in xNode) {
+            return xNode.innerHTML;
+        } else {
+            return xNode.textContent;
+        }
+    };
 
     * _getParsableNodes (xRootNode=this.xEditor.rootElement) {
         // recursive function
         try {
             for (let xNode of xRootNode.childNodes) {
@@ -32,11 +40,11 @@
     * getParagraphs () {
         try {
             let i = 0;
             for (let xNode of this._getParsableNodes()) {
                 this.lNode.push(xNode);
-                yield [i, xNode.innerHTML];
+                yield [i, this._getTextFromNode(xNode)];
                 i += 1;
             }
         } catch (e) {
             Cu.reportError(e);
         }
@@ -57,19 +65,24 @@
         }
     };
 
     getParagraph (iPara) {
         try {
-            return this.lNode[iPara].innerHTML;
+            return this._getTextFromNode(this.lNode[iPara]);
         } catch (e) {
             Cu.reportError(e);
         }
     };
 
     writeParagraph (iPara, sText) {
         try {
-            this.lNode[iPara].innerHTML = sText;
+            let xNode = this.lNode[iPara];
+            if ("innerHTML" in xNode) {
+                xNode.innerHTML = sText;
+            } else {
+                xNode.textContent = sText;
+            }
         } catch (e) {
             Cu.reportError(e);
         }
     };
 

Index: gc_lang/fr/tb/install.rdf
==================================================================
--- gc_lang/fr/tb/install.rdf
+++ gc_lang/fr/tb/install.rdf
@@ -13,11 +13,11 @@
     <em:unpack>true</em:unpack>
 
     <em:targetApplication>
       <Description>
         <em:id>{3550f703-e582-4d05-9a08-453d09bdfdc6}</em:id> <!-- thunderbird -->
-        <em:minVersion>45.8</em:minVersion>
-        <em:maxVersion>49.0</em:maxVersion>
+        <em:minVersion>45.8.0</em:minVersion>
+        <em:maxVersion>55.*</em:maxVersion>
       </Description>
     </em:targetApplication>
   </Description>
 </RDF>