Enable lock session action properly on join

It didn't always get enabled because the ACL state didn't notice a
change between being a local operator drawing offline and going online.

ChangeLog

@@ -15,6 +15,7 @@ Unreleased Version 2.2.0-pre
  * Fix: Don't add current color to the palette when creating it. Thanks xxxx for reporting.
  * Fix: Make exported palettes not start using the exported location to save changes to. Thanks xxxx for reporting.
  * Feature: Allow muting notifications for a window. Thanks Blozzom for suggesting.
+ * Fix: Enable the lock session menu option properly, it remained stuck disabled in some cases before.
 
 2023-07-31 Version 2.2.0-beta.6
  * Fix: Don't forget account password when entering a wrong session password.

src/desktop/mainwindow.cpp

@@ -2005,6 +2005,7 @@ void MainWindow::onServerLogin(bool join, const QString &joinPassword)
 	m_sessionSettings->setAuthenticated(m_doc->client()->isAuthenticated());
 	setDrawingToolsEnabled(true);
 	m_modtools->setEnabled(m_doc->client()->isModerator());
+	onOperatorModeChange(m_doc->canvas()->aclState()->amOperator());
 	getAction("reportabuse")->setEnabled(m_doc->client()->serverSupportsReports());
 	getAction("invitesession")->setEnabled(true);
 	if(m_chatbox->isCollapsed()) {