Fix caption glitch on open

Author: guiodic

src/AppMenuButtonGroup.cc

@@ -96,7 +96,7 @@ AppMenuButtonGroup::AppMenuButtonGroup(Decoration *decoration)
     connect(m_resetTimer, &QTimer::timeout, this, &AppMenuButtonGroup::resetButtons);
 
     m_menuLoadFallbackTimer = new QTimer(this);
-    m_menuLoadFallbackTimer->setInterval(2000);
+    m_menuLoadFallbackTimer->setInterval(750);
     m_menuLoadFallbackTimer->setSingleShot(true);
     connect(m_menuLoadFallbackTimer, &QTimer::timeout, this, [this]() {
         if (!m_menuLoadedOnce) {
@@ -148,6 +148,10 @@ AppMenuButtonGroup::AppMenuButtonGroup(Decoration *decoration)
 
     if (decoratedClient->hasApplicationMenu()) {
         onHasApplicationMenuChanged(true);
+    } else {
+        // Initial wait to see if a menu appears later during startup.
+        // This avoids the title appearing and then shifting.
+        m_menuLoadFallbackTimer->start(500);
     }
 }
 
@@ -366,9 +370,10 @@ void AppMenuButtonGroup::onMenuReadyForSearch()
 void AppMenuButtonGroup::onHasApplicationMenuChanged(bool hasMenu)
 {
     if (hasMenu) {
-        if (!m_menuLoadedOnce) {
-            m_menuLoadFallbackTimer->start();
-        }
+        m_resetTimer->stop();
+        m_menuLoadedOnce = false;
+        m_menuLoadFallbackTimer->start(750);
+        Q_EMIT menuUpdated();
 
         if (m_isMenuUpdateThrottled) {
             m_pendingMenuUpdate = true;
@@ -386,6 +391,7 @@ void AppMenuButtonGroup::onHasApplicationMenuChanged(bool hasMenu)
         // Defer reset to avoid flicker during window closure
         m_resetTimer->start();
         m_menuLoadedOnce = false;
+        Q_EMIT menuUpdated();
     }
 }
 
@@ -468,10 +474,6 @@ void AppMenuButtonGroup::updateAppMenuModel()
             return;
         }
 
-        m_resetTimer->stop();
-        m_menuLoadFallbackTimer->stop();
-        m_menuLoadedOnce = true;
-
         const auto actions = menu->actions();
         const int menuActionCount = actions.count();
 
@@ -566,6 +568,12 @@ void AppMenuButtonGroup::updateAppMenuModel()
             }
         }
 
+        if (menuActionCount > 0) {
+            m_resetTimer->stop();
+            m_menuLoadFallbackTimer->stop();
+            m_menuLoadedOnce = true;
+        }
+
         Q_EMIT menuUpdated();
     }
 }
@@ -682,6 +690,11 @@ bool AppMenuButtonGroup::menuLoadedOnce() const
     return m_menuLoadedOnce;
 }
 
+bool AppMenuButtonGroup::isWaitingForMenu() const
+{
+    return m_menuLoadFallbackTimer && m_menuLoadFallbackTimer->isActive();
+}
+
 void AppMenuButtonGroup::popupMenu(QMenu *menu, int buttonIndex)
 {
     // Stop any caching that may be in progress from a previously opened menu.

src/AppMenuButtonGroup.h

@@ -73,6 +73,7 @@ class AppMenuButtonGroup : public KDecoration3::DecorationButtonGroup
     qreal visibleWidth() const;
 
     bool menuLoadedOnce() const;
+    bool isWaitingForMenu() const;
 
     void handleHoverMove(const QPointF &pos);
 

src/Decoration.cc

@@ -1163,12 +1163,13 @@ void Decoration::paintCaption(QPainter *painter, const QRectF &repaintRegion) co
 {
     // 1. Pre-checks and data gathering
     const auto *decoratedClient = window();
-    const bool hasAppMenu = decoratedClient->hasApplicationMenu();
     const bool appMenuVisible = !m_menuButtons->buttons().isEmpty();
-    const bool menuLoaded = m_menuButtons->menuLoadedOnce();
+    const bool isWaitingForMenu = m_menuButtons->isWaitingForMenu();
+    const bool menuLoadedOnce = m_menuButtons->menuLoadedOnce();
+    const bool hasAppMenu = decoratedClient->hasApplicationMenu();
     const bool isTitleHidden = m_internalSettings->titleAlignment() == InternalSettings::TitleHidden;
 
-    if ((hasAppMenu && !menuLoaded) || isTitleHidden) {
+    if (isTitleHidden || (!menuLoadedOnce && (isWaitingForMenu || hasAppMenu))) {
         m_captionLimited = false;
         m_captionRect = QRectF();
         return;
@@ -1277,9 +1278,6 @@ void Decoration::paintCaption(QPainter *painter, const QRectF &repaintRegion) co
         m_captionCache.elidedCaption = fontMetrics.elidedText(fullCaption, Qt::ElideMiddle, drawingRect.width());
     }    
 
-    //qCDebug(category) << "Caption:     :" << decoratedClient->caption();
-    //qCDebug(category) << "   hasAppMenu: " << hasAppMenu;
-    //qCDebug(category) << "   menuLoaded: " << menuLoaded;
 
     painter->drawText(drawingRect, alignment | Qt::TextSingleLine | Qt::AlignVCenter, m_captionCache.elidedCaption);
     painter->restore();