Opaque resizing is defined by the style nowadays.

calendarviews/agenda/agendaview.cpp

@@ -48,7 +48,6 @@
 
 #include <KCalendarSystem>
 #include <KIconLoader> // for SmallIcon()
-#include <KGlobalSettings>
 #include <KHBox>
 #include <KMessageBox>
 #include <KServiceTypeTrader>
@@ -736,7 +735,6 @@ void AgendaView::init(const QDate &start, const QDate &end)
     /* Create agenda splitter */
     d->mSplitterAgenda = new QSplitter(Qt::Vertical, this);
     d->mGridLayout->addWidget(d->mSplitterAgenda, 1, 0);
-    d->mSplitterAgenda->setOpaqueResize(KGlobalSettings::opaqueResize());
 
     /* Create day name labels for agenda columns */
     d->mTopDayLabelsFrame = new KHBox(d->mSplitterAgenda);

calendarviews/multiagenda/multiagendaview.cpp

@@ -38,7 +38,6 @@ using namespace KPIM;
 #include <KCalCore/Event>
 
 #include <KCheckableProxyModel>
-#include <KGlobalSettings>
 #include <KLocalizedString>
 #include <QVBoxLayout>
 #include <KViewStateMaintainer>
@@ -162,7 +161,6 @@ MultiAgendaView::MultiAgendaView(QWidget *parent)
 
     d->mLeftSplitter = new QSplitter(Qt::Vertical, topSideBox);
     topSideBoxVBoxLayout->addWidget(d->mLeftSplitter);
-    d->mLeftSplitter->setOpaqueResize(KGlobalSettings::opaqueResize());
 
     d->mLabel = new QLabel(i18n("All Day"), d->mLeftSplitter);
     d->mLabel->setAlignment(Qt::AlignRight | Qt::AlignVCenter);
@@ -214,7 +212,6 @@ MultiAgendaView::MultiAgendaView(QWidget *parent)
 
     d->mRightSplitter = new QSplitter(Qt::Vertical, topSideBox);
     topSideBoxVBoxLayout->addWidget(d->mRightSplitter);
-    d->mRightSplitter->setOpaqueResize(KGlobalSettings::opaqueResize());
 
     connect(d->mLeftSplitter, &QSplitter::splitterMoved, this, &MultiAgendaView::resizeSplitters);
     connect(d->mRightSplitter, &QSplitter::splitterMoved, this, &MultiAgendaView::resizeSplitters);

kmail/kmmainwidget.cpp

@@ -619,7 +619,6 @@ void KMMainWidget::layoutSplitters()
     // The folder view is both the folder tree and the favorite folder view, if
     // enabled
 
-    const bool opaqueResize = KGlobalSettings::opaqueResize();
     const bool readerWindowAtSide = !mReaderWindowBelow && mReaderWindowActive;
     const bool readerWindowBelow = mReaderWindowBelow && mReaderWindowActive;
 
@@ -629,7 +628,6 @@ void KMMainWidget::layoutSplitters()
     QWidget *folderTreeWidget = mSearchAndTree;
     if (mFavoriteCollectionsView) {
         mFolderViewSplitter = new QSplitter(Qt::Vertical);
-        mFolderViewSplitter->setOpaqueResize(opaqueResize);
         //mFolderViewSplitter->setChildrenCollapsible( false );
         mFolderViewSplitter->addWidget(mFavoriteCollectionsView);
         mFavoriteCollectionsView->setParent(mFolderViewSplitter);
@@ -685,10 +683,8 @@ void KMMainWidget::layoutSplitters()
     // Set splitter properties
     //
     mSplitter1->setObjectName(QStringLiteral("splitter1"));
-    mSplitter1->setOpaqueResize(opaqueResize);
     //mSplitter1->setChildrenCollapsible( false );
     mSplitter2->setObjectName(QStringLiteral("splitter2"));
-    mSplitter2->setOpaqueResize(opaqueResize);
     //mSplitter2->setChildrenCollapsible( false );
 
     //

messageviewer/viewer/viewer_p.cpp

@@ -66,7 +66,6 @@
 #include <KRun>
 #include <KSelectAction>
 #include <KSharedConfigPtr>
-#include <KGlobalSettings>
 #include <KStandardGuiItem>
 #include <QTemporaryDir>
 #include <QTemporaryFile>
@@ -1596,7 +1595,6 @@ void ViewerPrivate::createWidgets()
 #ifndef QT_NO_TREEVIEW
     mSplitter->setStretchFactor(mSplitter->indexOf(mMimePartTree), 0);
 #endif
-    mSplitter->setOpaqueResize(KGlobalSettings::opaqueResize());
 }
 
 void ViewerPrivate::createActions()