Use Show desktop item instead of empty text in TabBox

If there are no windows for Alt+Tab the Show Desktop entry
is shown. This works better with both layouts and effects.
Before this change effects were not activated at all but
a fallback to the layouts was used. Concerning the layouts
some looked rather bad. E.g. Thumbnails did not show a
thumbnail but a legacy text had been shown.

When a window gets added to the empty list, the show desktop
window is removed and consequently when the last window goes
away the show desktop entry is added again.

There is a not considered corner case: if there is no desktop
window, the show desktop functionality is not available and
the behavior is unfortunately undefined. It is a corner case
as we can expect that there is always a desktop window when
using KWin. E.g. there is either Plasma Desktop or Netbook
and on PA there is always at least one window.

BUG: 260938
FIXED-IN: 4.9.0
REVIEW: 104379

tabbox/clientmodel.cpp

@@ -57,10 +57,7 @@ QVariant ClientModel::data(const QModelIndex& index, int role) const
         return QVariant();
 
     if (m_clientList.isEmpty()) {
-        if (role == EmptyRole)
+        return QVariant();
-            return true;
-        else
-            return i18n("*** No Windows ***");
     }
 
     int clientIndex = index.row() * columnCount() + index.column();
@@ -75,8 +72,6 @@ QVariant ClientModel::data(const QModelIndex& index, int role) const
     case DesktopNameRole: {
         return tabBox->desktopName(m_clientList[ clientIndex ]);
     }
-    case EmptyRole:
-        return false;
     case WIdRole:
         return qulonglong(m_clientList[ clientIndex ]->window());
     case MinimizedRole:
@@ -235,7 +230,7 @@ void ClientModel::createClientList(int desktop, bool partialReset)
         m_clientList.removeAll(c);
         m_clientList.prepend(c);
     }
-    if (tabBox->config().showDesktopMode() == TabBoxConfig::ShowDesktopClient) {
+    if (tabBox->config().showDesktopMode() == TabBoxConfig::ShowDesktopClient || m_clientList.isEmpty()) {
         TabBoxClient* desktopClient = tabBox->desktopClient();
         if (desktopClient)
             m_clientList.append(desktopClient);

tabbox/clientmodel.h

@@ -53,7 +53,6 @@ public:
         CaptionRole = Qt::UserRole + 1, ///< The caption of TabBoxClient
         DesktopNameRole = Qt::UserRole + 2, ///< The name of the desktop the TabBoxClient is on
         IconRole = Qt::UserRole + 3, // TODO: to be removed
-        EmptyRole = Qt::UserRole + 4, ///< Indicates if the model contains TabBoxClients
         WIdRole = Qt::UserRole + 5, ///< The window ID of TabBoxClient
         MinimizedRole = Qt::UserRole + 6, ///< TabBoxClient is minimized
         CloseableRole = Qt::UserRole + 7 ///< TabBoxClient can be closed

tabbox/declarative.cpp

@@ -69,9 +69,6 @@ QPixmap ImageProvider::requestPixmap(const QString &id, QSize *size, const QSize
     if (!index.isValid()) {
         return QDeclarativeImageProvider::requestPixmap(id, size, requestedSize);
     }
-    if (index.model()->data(index, ClientModel::EmptyRole).toBool()) {
-        return QDeclarativeImageProvider::requestPixmap(id, size, requestedSize);
-    }
     TabBoxClient* client = static_cast< TabBoxClient* >(index.model()->data(index, ClientModel::ClientRole).value<void *>());
     if (!client) {
         return QDeclarativeImageProvider::requestPixmap(id, size, requestedSize);

tabbox/tabboxhandler.cpp

@@ -119,7 +119,7 @@ void TabBoxHandlerPrivate::updateOutline()
     if (config.tabBoxMode() != TabBoxConfig::ClientTabBox)
         return;
 //     if ( c == NULL || !m_isShown || !c->isShown( true ) || !c->isOnCurrentDesktop())
-    if (!isShown || clientModel()->data(index, ClientModel::EmptyRole).toBool()) {
+    if (!isShown) {
         q->hideOutline();
         return;
     }
@@ -410,8 +410,7 @@ TabBoxClientList TabBoxHandler::clientList() const
 TabBoxClient* TabBoxHandler::client(const QModelIndex& index) const
 {
     if ((!index.isValid()) ||
-            (d->config.tabBoxMode() != TabBoxConfig::ClientTabBox) ||
+            (d->config.tabBoxMode() != TabBoxConfig::ClientTabBox))
-            (d->clientModel()->data(index, ClientModel::EmptyRole).toBool()))
         return NULL;
     TabBoxClient* c = static_cast< TabBoxClient* >(
                           d->clientModel()->data(index, ClientModel::ClientRole).value<void *>());