diff --git a/src/accountregdlg.cpp b/src/accountregdlg.cpp
index 8bfffd451..83dfcf14e 100644
--- a/src/accountregdlg.cpp
+++ b/src/accountregdlg.cpp
@@ -79,7 +79,7 @@ AccountRegDlg::AccountRegDlg(PsiCon *psi, QWidget *parent) : QDialog(parent), ps
 
     // Fields pane
     QVBoxLayout *fields_layout = new QVBoxLayout(ui_.page_fields);
-    fields_layout->setMargin(0);
+    fields_layout->setContentsMargins(0, 0, 0, 0);
     fields_container_ = new QScrollArea(ui_.page_fields);
     fields_layout->addWidget(fields_container_);
     fields_container_->setWidgetResizable(true);
diff --git a/src/actionlist.h b/src/actionlist.h
index 911a0d9e2..a521a91a6 100644
--- a/src/actionlist.h
+++ b/src/actionlist.h
@@ -22,10 +22,10 @@
 
 #include <QList>
 #include <QObject>
+#include <QStringList>
 
 class IconAction;
 class QString;
-class QStringList;
 
 class ActionList : public QObject {
     Q_OBJECT
diff --git a/src/activeprofiles_dbus.cpp b/src/activeprofiles_dbus.cpp
index 81c175742..c71637a6f 100644
--- a/src/activeprofiles_dbus.cpp
+++ b/src/activeprofiles_dbus.cpp
@@ -101,10 +101,10 @@ QString ActiveProfiles::Private::dbusName(QString prof)
     QString name = PSIDBUSNAME;
     name += ".";
     name
-        += encodeAlNumD(ApplicationInfo::homeDir(ApplicationInfo::ConfigLocation)).rightRef(qMax(0, 200 - name.size()));
+        += encodeAlNumD(ApplicationInfo::homeDir(ApplicationInfo::ConfigLocation)).right(qMax(0, 200 - name.size()));
     if (!prof.isEmpty()) {
         name += ".";
-        name += encodeAlNumD(prof).rightRef(qMax(0, 250 - name.size()));
+        name += encodeAlNumD(prof).right(qMax(0, 250 - name.size()));
     }
     return name;
 }
diff --git a/src/chateditproxy.cpp b/src/chateditproxy.cpp
index 5e7787ce0..111e40e33 100644
--- a/src/chateditproxy.cpp
+++ b/src/chateditproxy.cpp
@@ -30,7 +30,7 @@ ChatEditProxy::ChatEditProxy(QWidget *parent) :
     QWidget(parent), lineEditEnabled_(false), textEdit_(nullptr), layout_(nullptr)
 {
     layout_ = new QVBoxLayout(this);
-    layout_->setMargin(0);
+    layout_->setContentsMargins(0, 0, 0, 0);
     layout_->setSpacing(0);
 
     connect(PsiOptions::instance(), &PsiOptions::optionChanged, this, &ChatEditProxy::optionsChanged);
diff --git a/src/chatsplitter.cpp b/src/chatsplitter.cpp
index eb8590917..c429fa135 100644
--- a/src/chatsplitter.cpp
+++ b/src/chatsplitter.cpp
@@ -127,7 +127,7 @@ void ChatSplitter::updateLayout()
     delete layout_;
     splitter_ = new QSplitter(this);
     layout_   = new QVBoxLayout(this);
-    layout_->setMargin(0);
+    layout_->setContentsMargins(0, 0, 0, 0);
     layout_->addWidget(splitter_);
     splitter_->setOrientation(Qt::Vertical);
     splitter_->setVisible(splitterEnabled());
diff --git a/src/contactlistitemmenu.cpp b/src/contactlistitemmenu.cpp
index 1ac4c74cd..f31a9300e 100644
--- a/src/contactlistitemmenu.cpp
+++ b/src/contactlistitemmenu.cpp
@@ -45,7 +45,7 @@ ContactListItemMenu::ContactListItemMenu(ContactListItem *item, ContactListModel
         _lblTitle->setPalette(palette);
         _lblTitle->setAutoFillBackground(true);
         _lblTitle->setAlignment(Qt::AlignCenter);
-        _lblTitle->setMargin(6);
+        _lblTitle->setContentsMargins(6, 6, 6, 6);
         _lblTitle->setFont(font);
 
         QWidgetAction *waContextMenuTitle = new QWidgetAction(this);
diff --git a/src/eventdlg.cpp b/src/eventdlg.cpp
index dea318cea..0a8f86005 100644
--- a/src/eventdlg.cpp
+++ b/src/eventdlg.cpp
@@ -602,7 +602,7 @@ EventDlg::~EventDlg()
 void EventDlg::init()
 {
     QVBoxLayout *vb1 = new QVBoxLayout(this);
-    vb1->setMargin(4);
+    vb1->setContentsMargins(4, 4, 4, 4);
     vb1->setSpacing(4);
 
     // first row
@@ -775,7 +775,7 @@ void EventDlg::init()
     // http auth transaction id
     d->w_http_id            = new QWidget(this);
     QHBoxLayout *hb_http_id = new QHBoxLayout(d->w_http_id);
-    hb_http_id->setMargin(0);
+    hb_http_id->setContentsMargins(0, 0, 0, 0);
     hb_http_id->setSpacing(4);
     d->le_http_id = new QLineEdit(d->w_http_id);
     l             = new QLabel(tr("Transaction &identifier:"), d->w_http_id);
diff --git a/src/filetransdlg.cpp b/src/filetransdlg.cpp
index 4c5d3aa08..345eed4bb 100644
--- a/src/filetransdlg.cpp
+++ b/src/filetransdlg.cpp
@@ -490,7 +490,7 @@ FileRequestDlg::FileRequestDlg(const Jid &jid, PsiCon *psi, PsiAccount *pa, cons
 
     QFrame *     hb       = new QFrame(this);
     QHBoxLayout *hbLayout = new QHBoxLayout(hb);
-    hbLayout->setMargin(0);
+    hbLayout->setContentsMargins(0, 0, 0, 0);
     d->lb_identity = new QLabel(tr("Identity: "), hb);
     hbLayout->addWidget(d->lb_identity);
     d->cb_ident = d->psi->accountsComboBox(hb);
@@ -577,7 +577,7 @@ FileRequestDlg::FileRequestDlg(const QDateTime &ts, FileTransfer *ft, PsiAccount
     d->cb_ident           = nullptr;
     QFrame *     hb       = new QFrame(this);
     QHBoxLayout *hbLayout = new QHBoxLayout(hb);
-    hbLayout->setMargin(0);
+    hbLayout->setContentsMargins(0, 0, 0, 0);
     d->lb_identity = new QLabel(tr("Identity: "), hb);
     hbLayout->addWidget(d->lb_identity);
     d->lb_ident = new AccountLabel(hb);
diff --git a/src/mainwin.cpp b/src/mainwin.cpp
index 8d719772f..7d82891bf 100644
--- a/src/mainwin.cpp
+++ b/src/mainwin.cpp
@@ -366,7 +366,7 @@ MainWin::MainWin(bool _onTop, bool _asTool, PsiCon *psi) :
 #endif
     QMenu *viewMenu = new QMenu(tr("View"), this);
 
-    d->vb_roster->setMargin(layoutMargin);
+    d->vb_roster->setContentsMargins(layoutMargin, layoutMargin, layoutMargin, layoutMargin);
     d->vb_roster->setSpacing(layoutMargin);
 
     if (d->allInOne) {
diff --git a/src/mucconfigdlg.cpp b/src/mucconfigdlg.cpp
index ad19aca5a..67885e0ee 100644
--- a/src/mucconfigdlg.cpp
+++ b/src/mucconfigdlg.cpp
@@ -43,7 +43,7 @@ MUCConfigDlg::MUCConfigDlg(MUCManager *manager, QWidget *parent) : QDialog(paren
     setModal(false);
 
     QVBoxLayout *data_layout = new QVBoxLayout(ui_.pg_general_data);
-    data_layout->setMargin(0);
+    data_layout->setContentsMargins(0, 0, 0, 0);
 
     data_container_ = new QScrollArea(ui_.pg_general_data);
     data_layout->addWidget(data_container_);
diff --git a/src/options/opt_tree.cpp b/src/options/opt_tree.cpp
index ab4e7d2f3..e01ed09ba 100644
--- a/src/options/opt_tree.cpp
+++ b/src/options/opt_tree.cpp
@@ -22,7 +22,7 @@ QWidget *OptionsTabTree::widget()
 
     QVBoxLayout *layout = new QVBoxLayout(w);
     // layout->setSpacing(0);
-    layout->setMargin(0);
+    layout->setContentsMargins(0, 0, 0, 0);
 
     QLabel *lb = new QLabel(tr("Please note: This editor will change the options "
                                "directly. Pressing Cancel will not revert these changes."),
diff --git a/src/options/optionsdlgbase.cpp b/src/options/optionsdlgbase.cpp
index 0cd20c1fd..16924f1a7 100644
--- a/src/options/optionsdlgbase.cpp
+++ b/src/options/optionsdlgbase.cpp
@@ -330,7 +330,7 @@ void OptionsDlgBase::Private::openTab(const QString &id)
 
                 QVBoxLayout *vbox = new QVBoxLayout(w);
                 vbox->setSpacing(0);
-                vbox->setMargin(0);
+                vbox->setContentsMargins(0, 0, 0, 0);
 
                 tab->setParent(w);
                 vbox->addWidget(tab);
diff --git a/src/options/optionstab.cpp b/src/options/optionstab.cpp
index 700478256..a9410fd6e 100644
--- a/src/options/optionstab.cpp
+++ b/src/options/optionstab.cpp
@@ -141,7 +141,7 @@ void OptionsTabWidget::updateCurrent(int index)
     QWidget *w = currentWidget();
     if (!w2tab[w].initialized) {
         QVBoxLayout *vbox = new QVBoxLayout(w);
-        vbox->setMargin(5);
+        vbox->setContentsMargins(5, 5, 5, 5);
         OptionsTab *opttab = w2tab[w].tab;
 
         QWidget *tab = opttab->widget();
diff --git a/src/passdialog.cpp b/src/passdialog.cpp
index 18781f27d..531471dc0 100644
--- a/src/passdialog.cpp
+++ b/src/passdialog.cpp
@@ -33,7 +33,7 @@ PassDialog::PassDialog(const QString &jid, QWidget *parent) : QDialog(parent)
     setWindowTitle(tr("Wrong Account Password"));
 
     QVBoxLayout *mainLayout = new QVBoxLayout(this);
-    mainLayout->setMargin(6);
+    mainLayout->setContentsMargins(6, 6, 6, 6);
     mainLayout->setSpacing(6);
     QHBoxLayout *botLayout = new QHBoxLayout();
 
diff --git a/src/proxy.cpp b/src/proxy.cpp
index 7ca776d78..752accaa2 100644
--- a/src/proxy.cpp
+++ b/src/proxy.cpp
@@ -338,7 +338,7 @@ ProxyChooser::ProxyChooser(ProxyManager *m, QWidget *parent) : QWidget(parent)
     d->m = m;
     connect(m, SIGNAL(settingsChanged()), SLOT(pm_settingsChanged()));
     QHBoxLayout *hb = new QHBoxLayout(this);
-    hb->setMargin(0);
+    hb->setContentsMargins(0, 0, 0, 0);
     hb->setSpacing(4);
     d->cb_proxy = new QComboBox(this);
     d->cb_proxy->setSizePolicy(QSizePolicy(QSizePolicy::Expanding, d->cb_proxy->sizePolicy().verticalPolicy()));
diff --git a/src/psidbusnotifier.cpp b/src/psidbusnotifier.cpp
index 3e0a8ecec..9b651fb7c 100644
--- a/src/psidbusnotifier.cpp
+++ b/src/psidbusnotifier.cpp
@@ -67,7 +67,8 @@ class iiibiiay {
 #endif
     }
     iiibiiay() { }
-    static const int id;
+    static const decltype(qDBusRegisterMetaType<iiibiiay>()) id;
+
     int              width;
     int              height;
     int              rowstride;
@@ -78,7 +79,7 @@ class iiibiiay {
 };
 Q_DECLARE_METATYPE(iiibiiay)
 
-const int iiibiiay::id(qDBusRegisterMetaType<iiibiiay>());
+const decltype(qDBusRegisterMetaType<iiibiiay>()) iiibiiay::id{qDBusRegisterMetaType<iiibiiay>()};
 
 QDBusArgument &operator<<(QDBusArgument &a, const iiibiiay &i)
 {
diff --git a/src/psioptionseditor.cpp b/src/psioptionseditor.cpp
index 4250e13f5..47bf132cc 100644
--- a/src/psioptionseditor.cpp
+++ b/src/psioptionseditor.cpp
@@ -113,7 +113,7 @@ PsiOptionsEditor::PsiOptionsEditor(QWidget *parent) : QWidget(parent)
 
     QVBoxLayout *layout = new QVBoxLayout(this);
     layout->setSpacing(0);
-    layout->setMargin(0);
+    layout->setContentsMargins(0, 0, 0, 0);
 
     QHBoxLayout *filterLayout = new QHBoxLayout;
     le_filter                 = new QLineEdit(this);
diff --git a/src/psirosterwidget.cpp b/src/psirosterwidget.cpp
index ceadaf9f4..45a3b791a 100644
--- a/src/psirosterwidget.cpp
+++ b/src/psirosterwidget.cpp
@@ -106,7 +106,7 @@ PsiRosterWidget::PsiRosterWidget(QWidget *parent) :
     contactListPageView_(nullptr), filterPageView_(nullptr), contactListModel_(nullptr), filterModel_(nullptr)
 {
     QVBoxLayout *layout = new QVBoxLayout(this);
-    layout->setMargin(0);
+    layout->setContentsMargins(0, 0, 0, 0);
     layout->setSpacing(0);
 
     stackedWidget_ = new QStackedWidget(this);
@@ -119,7 +119,7 @@ PsiRosterWidget::PsiRosterWidget(QWidget *parent) :
     stackedWidget_->addWidget(contactListPage_);
 
     QVBoxLayout *contactListPageLayout = new QVBoxLayout(contactListPage_);
-    contactListPageLayout->setMargin(0);
+    contactListPageLayout->setContentsMargins(0, 0, 0, 0);
     contactListPageView_ = new PsiContactListView(contactListPage_);
     contactListPageView_->installEventFilter(this);
     contactListPageView_->setObjectName("contactListView");
@@ -132,7 +132,7 @@ PsiRosterWidget::PsiRosterWidget(QWidget *parent) :
     stackedWidget_->addWidget(filterPage_);
 
     QVBoxLayout *filterPageLayout = new QVBoxLayout(filterPage_);
-    filterPageLayout->setMargin(0);
+    filterPageLayout->setContentsMargins(0, 0, 0, 0);
     filterPageLayout->setSpacing(0);
 
     filterEdit_          = new ActionLineEdit(filterPage_);
diff --git a/src/registrationdlg.cpp b/src/registrationdlg.cpp
index c6a5a2c9d..d182136e3 100644
--- a/src/registrationdlg.cpp
+++ b/src/registrationdlg.cpp
@@ -147,7 +147,7 @@ RegistrationDlg::RegistrationDlg(const Jid &jid, PsiAccount *pa) : QDialog(nullp
     setWindowTitle(tr("Registration: %1").arg(d->jid.full()));
 
     QVBoxLayout *vb1 = new QVBoxLayout(this);
-    vb1->setMargin(4);
+    vb1->setContentsMargins(4, 4, 4, 4);
     d->lb_top = new QLabel(this);
     d->lb_top->setWordWrap(true);
     d->lb_top->setFrameStyle(QFrame::Panel | QFrame::Sunken);
diff --git a/src/rosteravatarframe.cpp b/src/rosteravatarframe.cpp
index 0a534f876..d44675c13 100644
--- a/src/rosteravatarframe.cpp
+++ b/src/rosteravatarframe.cpp
@@ -28,8 +28,8 @@
 RosterAvatarFrame::RosterAvatarFrame(QWidget *parent) : QFrame(parent), statusMessage_("")
 {
     ui_.setupUi(this);
-    layout()->setMargin(
-        PsiOptions::instance()->getOption("options.ui.contactlist.roster-avatar-frame.avatar.margin").toInt());
+    auto margin = PsiOptions::instance()->getOption("options.ui.contactlist.roster-avatar-frame.avatar.margin").toInt();
+    layout()->setContentsMargins(margin, margin, margin, margin);
     layout()->setSpacing(0);
     setMoodIcon("pep/mood");
     setActivityIcon("pep/activities");
@@ -142,9 +142,10 @@ void RosterAvatarFrame::optionChanged(QString option)
         drawAvatar();
     else if (option == "options.ui.look.font.contactlist")
         setFont();
-    else if (option == "options.ui.contactlist.roster-avatar-frame.avatar.margin")
-        layout()->setMargin(PsiOptions::instance()->getOption(option).toInt());
-    else if (option == "options.extended-presence.tune.publish") {
+    else if (option == "options.ui.contactlist.roster-avatar-frame.avatar.margin") {
+        auto margin = PsiOptions::instance()->getOption(option).toInt();
+        layout()->setContentsMargins(margin, margin, margin, margin);
+    } else if (option == "options.extended-presence.tune.publish") {
         bool publishingEnabled = PsiOptions::instance()->getOption(option).toBool();
         ui_.tb_tune->setChecked(publishingEnabled);
     }
diff --git a/src/showtextdlg.cpp b/src/showtextdlg.cpp
index 8625dbd7f..e34125600 100644
--- a/src/showtextdlg.cpp
+++ b/src/showtextdlg.cpp
@@ -42,7 +42,7 @@ ShowTextDlg::ShowTextDlg(const QString &fname, bool rich, QWidget *parent) : QDi
     }
 
     QVBoxLayout *vb1 = new QVBoxLayout(this);
-    vb1->setMargin(8);
+    vb1->setContentsMargins(8, 8, 8, 8);
     QTextEdit *te = new QTextEdit(this);
     te->setReadOnly(true);
     te->setAcceptRichText(rich);
@@ -71,7 +71,7 @@ ShowTextDlg::ShowTextDlg(const QString &text, bool nonfile, bool rich, QWidget *
     setAttribute(Qt::WA_DeleteOnClose);
 
     QVBoxLayout *vb1 = new QVBoxLayout(this);
-    vb1->setMargin(8);
+    vb1->setContentsMargins(8, 8, 8, 8);
     QTextEdit *te = new QTextEdit(this);
     te->setReadOnly(true);
     te->setAcceptRichText(rich);
diff --git a/src/statusdlg.cpp b/src/statusdlg.cpp
index eb8716dcc..e056088dd 100644
--- a/src/statusdlg.cpp
+++ b/src/statusdlg.cpp
@@ -53,7 +53,7 @@ StatusShowDlg::StatusShowDlg(const UserListItem &u) : QDialog(nullptr)
     setAttribute(Qt::WA_DeleteOnClose);
     // build the dialog
     QVBoxLayout *vb = new QVBoxLayout(this);
-    vb->setMargin(8);
+    vb->setContentsMargins(8, 8, 8, 8);
     PsiTextView *te = new PsiTextView(this);
     vb->addWidget(te);
     QHBoxLayout *hb = new QHBoxLayout;
@@ -150,7 +150,7 @@ void StatusSetDlg::init()
 
     // build the dialog
     QVBoxLayout *vb = new QVBoxLayout(this);
-    vb->setMargin(8);
+    vb->setContentsMargins(8, 8, 8, 8);
     QHBoxLayout *hb1 = new QHBoxLayout;
     vb->addLayout(hb1);
 
diff --git a/src/tabs/tabdlg.cpp b/src/tabs/tabdlg.cpp
index 1229efae5..ff6f7d588 100644
--- a/src/tabs/tabdlg.cpp
+++ b/src/tabs/tabdlg.cpp
@@ -116,7 +116,7 @@ TabDlg::TabDlg(TabManager *tabManager, const QString &geometryOption, TabDlgDele
         delegate_->tabWidgetCreated(this, tabWidget_);
 
     QVBoxLayout *vert1 = new QVBoxLayout(this);
-    vert1->setMargin(1);
+    vert1->setContentsMargins(1, 1, 1, 1);
     vert1->addWidget(tabWidget_);
 
     setAcceptDrops(true);
@@ -254,7 +254,7 @@ void TabDlg::tab_aboutToShowMenu(QMenu *menu)
     int tabDlgMetaType = qRegisterMetaType<TabDlg *>("TabDlg*");
     for (TabDlg *tabSet : tabManager_->tabSets()) {
         QAction *act = sendTo->addAction(tabSet->desiredCaption());
-        act->setData(QVariant(tabDlgMetaType, &tabSet));
+        act->setData(QVariant(QMetaType(tabDlgMetaType), &tabSet));
         act->setEnabled(tabSet != this);
     }
     connect(sendTo, SIGNAL(triggered(QAction *)), SLOT(menu_sendTabTo(QAction *)));
diff --git a/src/vcardphotodlg.cpp b/src/vcardphotodlg.cpp
index 07325f248..4071079a9 100644
--- a/src/vcardphotodlg.cpp
+++ b/src/vcardphotodlg.cpp
@@ -25,7 +25,7 @@ ShowPhotoDlg::ShowPhotoDlg(QWidget *parent, QPixmap &pixmap) : QDialog(parent),
     toolbar             = new QToolBar(this);
     toolbar->setToolButtonStyle(Qt::ToolButtonIconOnly);
     layout->setSpacing(0);
-    layout->setMargin(0);
+    layout->setContentsMargins(0, 0, 0, 0);
     layout->addWidget(toolbar);
     layout->addWidget(label);
 
diff --git a/src/whiteboarding/wbdlg.cpp b/src/whiteboarding/wbdlg.cpp
index 04365f0e5..7ac1e26f0 100644
--- a/src/whiteboarding/wbdlg.cpp
+++ b/src/whiteboarding/wbdlg.cpp
@@ -24,10 +24,12 @@
 #include "wbdlg.h"
 
 #include "accountlabel.h"
+#include "iconaction.h"
 #include "iconset.h"
 #include "psiaccount.h"
 #include "stretchwidget.h"
 
+#include <QActionGroup>
 #include <QColorDialog>
 #include <QHBoxLayout>
 #include <QMessageBox>
diff --git a/src/whiteboarding/wbscene.cpp b/src/whiteboarding/wbscene.cpp
index 33c6f67ec..cf8e87747 100644
--- a/src/whiteboarding/wbscene.cpp
+++ b/src/whiteboarding/wbscene.cpp
@@ -103,7 +103,7 @@ void WbScene::ungroup()
             if (group.nodeName() == "g") {
                 QDomNodeList children = group.childNodes();
 
-                QMatrix groupTransform = WbItem::parseSvgTransform(group.attribute("transform"));
+                QTransform groupTransform = WbItem::parseSvgTransform(group.attribute("transform"));
 
                 for (int i = children.size() - 1; i >= 0; i--) {
                     QDomElement child = children.at(i).toElement();
@@ -111,7 +111,7 @@ void WbScene::ungroup()
 
                         if (!groupTransform.isIdentity()) {
                             // combine the transformations of the group and the child
-                            QMatrix childTransform = WbItem::parseSvgTransform(child.attribute("transform"));
+                            QTransform childTransform = WbItem::parseSvgTransform(child.attribute("transform"));
                             session_->setAttribute(child, "transform",
                                                    WbItem::toSvgTransform(childTransform * groupTransform));
                         }
diff --git a/src/x11windowsystem.cpp b/src/x11windowsystem.cpp
index ad81defca..79da3910d 100644
--- a/src/x11windowsystem.cpp
+++ b/src/x11windowsystem.cpp
@@ -1,55 +1,26 @@
 #include "x11windowsystem.h"
 
+#if QT_VERSION < QT_VERSION_CHECK(6,0,0)
 #include <QX11Info>
+#else
+#include <QGuiApplication>
+#endif
 #include <X11/Xlib.h>
 #include <X11/Xutil.h> // needed for WM_CLASS hinting
 
 const long       MAX_PROP_SIZE              = 100000;
 X11WindowSystem *X11WindowSystem::_instance = nullptr;
 
-bool X11WindowSystem::isValid() const {
-    return QX11Info::isPlatformX11();
-}
-
-void X11WindowSystem::x11wmClass(WId wid, QString resName)
-{
-#if defined(LIMIT_X11_USAGE)
-    return;
-#endif
-
-    if (!QX11Info::isPlatformX11()) // Avoid crashes if launched in Wayland
-        return;
-
-    // Display *dsp = x11Display();                 // get the display
-    // WId win = winId();                           // get the window
-    XClassHint classhint; // class hints
-    // Get old class hint. It is important to save old class name
-    XGetClassHint(QX11Info::display(), wid, &classhint);
-    XFree(classhint.res_name);
 
-    const QByteArray latinResName = resName.toLatin1();
-    classhint.res_name            = const_cast<char *>(latinResName.data()); // res_name
-    XSetClassHint(QX11Info::display(), wid, &classhint);                     // set the class hints
+namespace {
 
-    XFree(classhint.res_class);
-}
-
-void X11WindowSystem::bringToFront(QWidget *w)
-{
-    if (QX11Info::isPlatformX11()) {
-        // If we're not on the current desktop, do the hide/show trick
-        long   dsk, curr_dsk;
-        Window win = w->winId();
-        if (X11WindowSystem::instance()->desktopOfWindow(&win, &dsk)
-            && X11WindowSystem::instance()->currentDesktop(&curr_dsk)) {
-            // qDebug() << "bringToFront current desktop=" << curr_dsk << " windowDesktop=" << dsk;
-            if ((dsk != curr_dsk) && (dsk != -1)) { // second condition for sticky windows
-                w->hide();
-            }
-        }
-    }
-
-    // FIXME: multi-desktop hacks for Win and Mac required
+bool isPlatformX11() {
+#if QT_VERSION < QT_VERSION_CHECK(6,0,0)
+    return QX11Info::isPlatformX11());
+#else
+    auto x11app = qApp->nativeInterface<QNativeInterface::QX11Application>();
+    return !!x11app;
+#endif
 }
 
 //>>>-- Nathaniel Gray -- Caltech Computer Science ------>
@@ -63,7 +34,7 @@ static bool getCardinal32Prop(Display *display, Window win, char *propName, long
     return false;
 #endif
 
-    if (!QX11Info::isPlatformX11()) // Avoid crashes if launched in Wayland
+    if (!isPlatformX11()) // Avoid crashes if launched in Wayland
         return false;
 
     Atom          nameAtom, typeAtom, actual_type_return;
@@ -78,7 +49,7 @@ static bool getCardinal32Prop(Display *display, Window win, char *propName, long
         return false;
     }
 
-    // Try to get the property
+           // Try to get the property
     result
         = XGetWindowProperty(display, win, nameAtom, 0, 1, False, typeAtom, &actual_type_return, &actual_format_return,
                              &nitems_return, &bytes_after_return, reinterpret_cast<unsigned char **>(&result_array));
@@ -99,10 +70,75 @@ static bool getCardinal32Prop(Display *display, Window win, char *propName, long
     return true;
 }
 
+auto getDisplay() {
+#if QT_VERSION < QT_VERSION_CHECK(6,0,0)
+    return QX11Info::display());
+#else
+    auto x11app = qApp->nativeInterface<QNativeInterface::QX11Application>();
+    return x11app->display();
+#endif
+}
+
+auto getRootWindow() {
+#if QT_VERSION < QT_VERSION_CHECK(6,0,0)
+    return QX11Info::appRootWindow();
+#else
+    auto x11app = qApp->nativeInterface<QNativeInterface::QX11Application>();
+    return DefaultRootWindow(x11app->display());
+#endif
+}
+
+}
+
+bool X11WindowSystem::isValid() const {
+    return ::isPlatformX11();
+}
+
+void X11WindowSystem::x11wmClass(WId wid, QString resName)
+{
+#if defined(LIMIT_X11_USAGE)
+    return;
+#endif
+
+    if (!isValid()) // Avoid crashes if launched in Wayland
+        return;
+
+    Display *dsp = getDisplay();                 // get the display
+    // WId win = winId();                           // get the window
+    XClassHint classhint; // class hints
+    // Get old class hint. It is important to save old class name
+    XGetClassHint(dsp, wid, &classhint);
+    XFree(classhint.res_name);
+
+    const QByteArray latinResName = resName.toLatin1();
+    classhint.res_name            = const_cast<char *>(latinResName.data()); // res_name
+    XSetClassHint(dsp, wid, &classhint);                     // set the class hints
+
+    XFree(classhint.res_class);
+}
+
+void X11WindowSystem::bringToFront(QWidget *w)
+{
+    if (isValid()) {
+        // If we're not on the current desktop, do the hide/show trick
+        long   dsk, curr_dsk;
+        Window win = w->winId();
+        if (X11WindowSystem::instance()->desktopOfWindow(&win, &dsk)
+            && X11WindowSystem::instance()->currentDesktop(&curr_dsk)) {
+            // qDebug() << "bringToFront current desktop=" << curr_dsk << " windowDesktop=" << dsk;
+            if ((dsk != curr_dsk) && (dsk != -1)) { // second condition for sticky windows
+                w->hide();
+            }
+        }
+    }
+
+    // FIXME: multi-desktop hacks for Win and Mac required
+}
+
 // Get the desktop number that a window is on
 bool X11WindowSystem::desktopOfWindow(Window *window, long *desktop)
 {
-    Display *display = QX11Info::display();
+    Display *display = getDisplay();
     bool     result  = getCardinal32Prop(display, *window, const_cast<char *>("_NET_WM_DESKTOP"), desktop);
     // if( result )
     //    qDebug("Desktop: " + QString::number(*desktop));
@@ -113,10 +149,10 @@ bool X11WindowSystem::desktopOfWindow(Window *window, long *desktop)
 bool X11WindowSystem::currentDesktop(long *desktop)
 {
     Window   rootWin;
-    Display *display = QX11Info::display();
+    Display *display = getDisplay();
     bool     result;
 
-    rootWin = RootWindow(QX11Info::display(), XDefaultScreen(QX11Info::display()));
+    rootWin = RootWindow(display, XDefaultScreen(display));
     result  = getCardinal32Prop(display, rootWin, const_cast<char *>("_NET_CURRENT_DESKTOP"), desktop);
     // if( result )
     //    qDebug("Current Desktop: " + QString::number(*desktop));
@@ -156,7 +192,7 @@ X11WindowSystem::X11WindowSystem()
         atoms[i] = 0;
 
 #if !defined(LIMIT_X11_USAGE)
-    XInternAtoms(QX11Info::display(), const_cast<char **>(names), atomsCount, true, atoms);
+    XInternAtoms(getDisplay(), const_cast<char **>(names), atomsCount, true, atoms);
 #endif
 
     i = atomsCount;
@@ -191,8 +227,9 @@ QRect X11WindowSystem::windowRect(Window win)
     Window       w_unused;
     int          x, y;
     unsigned int w, h, junk;
-    XGetGeometry(QX11Info::display(), win, &w_unused, &x, &y, &w, &h, &junk, &junk);
-    XTranslateCoordinates(QX11Info::display(), win, QX11Info::appRootWindow(), 0, 0, &x, &y, &w_unused);
+    Display *display = getDisplay();
+    XGetGeometry(display, win, &w_unused, &x, &y, &w, &h, &junk, &junk);
+    XTranslateCoordinates(display, win, getRootWindow(), 0, 0, &x, &y, &w_unused);
 
     Atom           type_ret;
     int            format_ret;
@@ -200,7 +237,7 @@ QRect X11WindowSystem::windowRect(Window win)
     unsigned long  nitems_ret, unused;
     const Atom     XA_CARDINAL = Atom(6);
     if (net_frame_extents != None
-        && XGetWindowProperty(QX11Info::display(), win, net_frame_extents, 0l, 4l, False, XA_CARDINAL, &type_ret,
+        && XGetWindowProperty(display, win, net_frame_extents, 0l, 4l, False, XA_CARDINAL, &type_ret,
                               &format_ret, &nitems_ret, &unused, &data_ret)
             == Success) {
         if (type_ret == XA_CARDINAL && format_ret == 32 && nitems_ret == 4) {
@@ -221,6 +258,7 @@ QRect X11WindowSystem::windowRect(Window win)
 // Determine if window is obscured by other windows
 bool X11WindowSystem::isWindowObscured(QWidget *widget, bool alwaysOnTop)
 {
+    Display *display = getDisplay();
     if (net_wm_state_above != None) {
         if (!alwaysOnTop)
             ignoredWindowStates.insert(net_wm_state_above);
@@ -243,7 +281,7 @@ bool X11WindowSystem::isWindowObscured(QWidget *widget, bool alwaysOnTop)
 
     if (net_client_list_stacking != None) {
         QRect winRect = windowRect(win);
-        if (XGetWindowProperty(QX11Info::display(), QX11Info::appRootWindow(), net_client_list_stacking, 0,
+        if (XGetWindowProperty(display, getRootWindow(), net_client_list_stacking, 0,
                                MAX_PROP_SIZE, False, XA_WINDOW, &type_ret, &format_ret, &nitems_ret, &unused, &data_ret)
             == Success) {
             if (type_ret == XA_WINDOW && format_ret == 32) {
@@ -291,9 +329,10 @@ bool X11WindowSystem::windowHasOnlyTypes(Window win, const QSet<Atom> &allowedTy
     int            format_ret;
     unsigned char *data_ret;
     unsigned long  nitems_ret, unused;
+    Display *display = getDisplay();
 
     if (net_wm_window_type != None
-        && XGetWindowProperty(QX11Info::display(), win, net_wm_window_type, 0l, 2048l, False, XA_ATOM, &type_ret,
+        && XGetWindowProperty(display, win, net_wm_window_type, 0l, 2048l, False, XA_ATOM, &type_ret,
                               &format_ret, &nitems_ret, &unused, &data_ret)
             == Success) {
         if (type_ret == XA_ATOM && format_ret == 32 && nitems_ret > 0) {
@@ -319,8 +358,10 @@ bool X11WindowSystem::windowHasAnyOfStates(Window win, const QSet<Atom> &filtere
     int            format_ret;
     unsigned char *data_ret;
     unsigned long  nitems_ret, unused;
+    Display *display = getDisplay();
+
     if (net_wm_state != None
-        && XGetWindowProperty(QX11Info::display(), win, net_wm_state, 0l, 2048l, False, XA_ATOM, &type_ret, &format_ret,
+        && XGetWindowProperty(display, win, net_wm_state, 0l, 2048l, False, XA_ATOM, &type_ret, &format_ret,
                               &nitems_ret, &unused, &data_ret)
             == Success) {
         if (type_ret == XA_ATOM && format_ret == 32 && nitems_ret > 0) {
diff --git a/src/xmlconsole.cpp b/src/xmlconsole.cpp
index c86d47e7a..7d21b66d3 100644
--- a/src/xmlconsole.cpp
+++ b/src/xmlconsole.cpp
@@ -181,7 +181,7 @@ XmlPrompt::XmlPrompt(QWidget *parent) : QDialog(parent)
     setWindowTitle(tr("XML Input"));
 
     QVBoxLayout *vb1 = new QVBoxLayout(this);
-    vb1->setMargin(8);
+    vb1->setContentsMargins(8, 8, 8, 8);
 
     te = new QTextEdit(this);
     te->setAcceptRichText(false);
diff --git a/version b/version
index 4fb56b506..66bc8a89d 100644
--- a/version
+++ b/version
@@ -1 +1 @@
-1.5.1670 (2024-03-15, f8711b3e)
+1.5.1671 (2024-03-15, d8f0998f)