better lexer name handling

mainwindow.cpp

@@ -111,6 +111,11 @@ void MainWindow::setupActions()
     connect(lexerNoneAction, &QAction::triggered, this, [this](){
         if (SciEdit *editor = m_tabWidget->currentEditor()) {
             editor->setLexer(nullptr);
+            const int docId = m_tabWidget->currentDocumentId();
+            if (docId >= 0) {
+                m_documentManager->setDocumentLanguage(docId, QString());
+            }
+            updateStatusBar();
         }
     });
 
@@ -219,6 +224,11 @@ void MainWindow::applyLexer(const QString &lexerName)
     if (SciEdit *editor = m_tabWidget->currentEditor()) {
         Scintilla::ILexer5 * lexer = CreateLexer(lexerName.toStdString().c_str());
         editor->setLexer(lexer);
+        const int docId = m_tabWidget->currentDocumentId();
+        if (docId >= 0) {
+            m_documentManager->setDocumentLanguage(docId, lexerName);
+        }
+        updateStatusBar();
     }
 }
 
@@ -326,7 +336,8 @@ void MainWindow::updateStatusBar()
         int docId = m_tabWidget->currentDocumentId();
         if (docId >= 0) {
             QString encoding = m_documentManager->getDocumentEncoding(docId);
-            QString language = m_documentManager->getDocumentLanguage(docId);
+            const QString lexerName = m_documentManager->getDocumentLanguage(docId);
+            const QString language = lexerName.isEmpty() ? QStringLiteral("Plain Text") : LexerGroupActionMenu::displayName(lexerName);
             
             m_encodingStatusLabel->setText(encoding);
             m_languageStatusLabel->setText(language);