Unredirection patch for kwin 5.21

unredirect.patch

diff --git a/composite.cpp b/composite.cpp
index c529f398e..ce5b0bd08 100644
--- a/composite.cpp
+++ b/composite.cpp
@@ -109,11 +109,16 @@ Compositor::Compositor(QObject* workspace)
     : QObject(workspace)
     , m_state(State::Off)
     , m_selectionOwner(nullptr)
+    , forceUnredirectCheck(false)
     , m_scene(nullptr)
 {
     connect(options, &Options::configChanged, this, &Compositor::configChanged);
     connect(options, &Options::animationSpeedChanged, this, &Compositor::configChanged);
 
+    connect(&unredirectTimer, &QTimer::timeout, this, &Compositor::delayedCheckUnredirect);
+    connect(options, &Options::unredirectFullscreenChanged, this, &Compositor::delayedCheckUnredirect);
+    unredirectTimer.setSingleShot(true);
+
     // 2 sec which should be enough to restart the compositor.
     static const int compositorLostMessageDelay = 2000;
 
@@ -705,6 +710,54 @@ bool Compositor::isActive()
     return m_state == State::On;
 }
 
+void Compositor::checkUnredirect()
+{
+    checkUnredirect(false);
+}
+
+// force is needed when the list of windows changes (e.g. a window goes away)
+void Compositor::checkUnredirect(bool force)
+{
+    if (!isActive() || !m_scene->overlayWindow() || m_scene->overlayWindow()->window() == 0 || !options->isUnredirectFullscreen())
+        return;
+    if (force)
+        forceUnredirectCheck = true;
+    if (!unredirectTimer.isActive())
+        unredirectTimer.start(0);
+}
+
+void Compositor::delayedCheckUnredirect()
+{
+    if (!isActive() || !m_scene->overlayWindow() || m_scene->overlayWindow()->window() == 0 || !(options->isUnredirectFullscreen() || sender() == options))
+        return;
+    QList<Toplevel*> list;
+    bool changed = forceUnredirectCheck;
+    foreach (X11Client * c, Workspace::self()->clientList())
+        list.append(c);
+    foreach (Unmanaged * c, Workspace::self()->unmanagedList())
+        list.append(c);
+    foreach (Toplevel * c, list) {
+        if (c->updateUnredirectedState()) {
+            changed = true;
+            break;
+        }
+    }
+    // no desktops, no Deleted ones
+    if (!changed)
+        return;
+    forceUnredirectCheck = false;
+    // Cut out parts from the overlay window where unredirected windows are,
+    // so that they are actually visible.
+    const QSize &s = screens()->size();
+    QRegion reg(0, 0, s.width(), s.height());
+    foreach (Toplevel * c, list) {
+        if (c->unredirected())
+            reg -= c->frameGeometry();
+    }
+    m_scene->overlayWindow()->setShape(reg);
+    addRepaint(reg);
+}
+
 WaylandCompositor::WaylandCompositor(QObject *parent)
     : Compositor(parent)
 {
diff --git a/composite.h b/composite.h
index a904fd114..d15632156 100644
--- a/composite.h
+++ b/composite.h
@@ -50,6 +50,13 @@ public:
      */
     void scheduleRepaint();
 
+    /**
+     * Checks for possibly unredirectable windows.
+     */
+    void checkUnredirect();
+    void checkUnredirect(bool force);
+    void delayedCheckUnredirect();
+
     /**
      * Toggles compositing, that is if the Compositor is suspended it will be resumed
      * and if the Compositor is active it will be suspended.
@@ -138,6 +145,8 @@ private:
     QTimer m_releaseSelectionTimer;
     QList<xcb_atom_t> m_unusedSupportProperties;
     QTimer m_unusedSupportPropertyTimer;
+    QTimer unredirectTimer;
+    bool forceUnredirectCheck;
     Scene *m_scene;
     int m_framesToTestForSafety = 3;
     QMap<RenderLoop *, AbstractOutput *> m_renderLoops;
diff --git a/deleted.cpp b/deleted.cpp
index a93fa8da5..13cdbc633 100644
--- a/deleted.cpp
+++ b/deleted.cpp
@@ -297,5 +297,10 @@ void Deleted::removeTransientFor(Deleted *parent)
     m_transientFor.removeAll(parent);
 }
 
+bool Deleted::shouldUnredirect() const
+{
+    return false;
+}
+
 } // namespace
 
diff --git a/deleted.h b/deleted.h
index 3d545894c..a99aa5b33 100644
--- a/deleted.h
+++ b/deleted.h
@@ -168,6 +168,8 @@ public:
     bool isOutline() const override {
         return m_wasOutline;
     }
+protected:
+    bool shouldUnredirect() const override;
 
 private Q_SLOTS:
     void mainClientClosed(KWin::Toplevel *client);
diff --git a/effects.cpp b/effects.cpp
index 13a30abc0..c862f668e 100644
--- a/effects.cpp
+++ b/effects.cpp
@@ -627,6 +627,7 @@ void EffectsHandlerImpl::setActiveFullScreenEffect(Effect* e)
     }
     const bool activeChanged = (e == nullptr || fullscreen_effect == nullptr);
     fullscreen_effect = e;
+    m_compositor->checkUnredirect();
     emit activeFullScreenEffectChanged();
     if (activeChanged) {
         emit hasActiveFullScreenEffectChanged();
diff --git a/inputpanelv1client.h b/inputpanelv1client.h
index 2491c46d5..25c6418bd 100644
--- a/inputpanelv1client.h
+++ b/inputpanelv1client.h
@@ -35,6 +35,7 @@ public:
     bool isResizable() const override { return false; }
     bool isMovable() const override { return false; }
     bool isMovableAcrossScreens() const override { return false; }
+    bool shouldUnredirect() const override { return false; }
     bool acceptsFocus() const override { return false; }
     void closeWindow() override {}
     bool takeFocus() override { return false; }
diff --git a/internal_client.cpp b/internal_client.cpp
index a01da4b52..55a72396b 100644
--- a/internal_client.cpp
+++ b/internal_client.cpp
@@ -572,4 +572,9 @@ void InternalClient::updateInternalWindowGeometry()
     commitGeometry(clientRectToFrameRect(m_internalWindow->geometry()));
 }
 
+bool InternalClient::shouldUnredirect() const
+{
+    return false;
+}
+
 }
diff --git a/internal_client.h b/internal_client.h
index 187c78f32..13097a299 100644
--- a/internal_client.h
+++ b/internal_client.h
@@ -33,6 +33,7 @@ public:
     QPoint clientContentPos() const override;
     QSize minSize() const override;
     QSize maxSize() const override;
+    bool shouldUnredirect() const override;
     QRect transparentRect() const override;
     NET::WindowType windowType(bool direct = false, int supported_types = 0) const override;
     double opacity() const override;
diff --git a/kcmkwin/kwincompositing/compositing.ui b/kcmkwin/kwincompositing/compositing.ui
index 398043fa0..24e20f2a3 100644
--- a/kcmkwin/kwincompositing/compositing.ui
+++ b/kcmkwin/kwincompositing/compositing.ui
@@ -323,6 +323,18 @@ Alternatively, you might want to use the XRender backend instead.</string>
      </item>
     </widget>
    </item>
+   <item row="14" column="1">
+    <widget class="QCheckBox" name="kcfg_unredirectFullscreen">
+     <property name="toolTip">
+      <string>Applications do not have to set any hint to suspend compositing when the window is full-screen.
+              This delivers lower latency and has no delay when compared to the other option.
+              Some people have reported crashes under Intel, but I am not sure if this is the case.</string>
+     </property>
+     <property name="text">
+      <string>Suspend compositor for full-screen windows</string>
+     </property>
+    </widget>
+   </item>
   </layout>
  </widget>
  <customwidgets>
diff --git a/kcmkwin/kwincompositing/kwincompositing_setting.kcfg b/kcmkwin/kwincompositing/kwincompositing_setting.kcfg
index 7278d09b7..d2fa506f3 100644
--- a/kcmkwin/kwincompositing/kwincompositing_setting.kcfg
+++ b/kcmkwin/kwincompositing/kwincompositing_setting.kcfg
@@ -79,6 +79,10 @@
            <default>LatencyMedium</default>
        </entry>
 
+       <entry name="unredirectFullscreen" key="UnredirectFullscreen" type="Bool">
+           <default>true</default>
+       </entry>
+
     </group>
 
 </kcfg>
diff --git a/kcmkwin/kwinrules/rulesmodel.cpp b/kcmkwin/kwinrules/rulesmodel.cpp
index a3ad8ade0..aaf04ee16 100644
--- a/kcmkwin/kwinrules/rulesmodel.cpp
+++ b/kcmkwin/kwinrules/rulesmodel.cpp
@@ -639,6 +639,11 @@ void RulesModel::populateRuleList()
                          RulePolicy::ForceRule, RuleItem::Boolean,
                          i18n("Block compositing"), i18n("Appearance & Fixes"),
                          QIcon::fromTheme("composite-track-on")));
+
+    addRule(new RuleItem(QLatin1String("allowunredirect"),
+                         RulePolicy::ForceRule, RuleItem::Boolean,
+                         i18n("Allow unredirect"), i18n("Appearance & Fixes"),
+                         QIcon::fromTheme("composite-track-on")));
 }
 
 
diff --git a/kwin.kcfg b/kwin.kcfg
index 7485efc7f..af496d6d2 100644
--- a/kwin.kcfg
+++ b/kwin.kcfg
@@ -239,6 +239,9 @@
             <min>4</min>
             <max>6</max>
         </entry>
+        <entry name="UnredirectFullscreen" type="Bool">
+            <default>false</default>
+        </entry>
         <entry name="GLPlatformInterface" type="String">
             <default>glx</default>
         </entry>
diff --git a/layers.cpp b/layers.cpp
index a82fed2b8..bf384ad2e 100644
--- a/layers.cpp
+++ b/layers.cpp
@@ -715,6 +715,9 @@ QList<Toplevel *> Workspace::xStackingOrder() const
     if (m_xStackingDirty) {
         const_cast<Workspace*>(this)->updateXStackingOrder();
     }
+    if (m_compositor) {
+        const_cast<Workspace*>(this)->m_compositor->checkUnredirect();
+    }
     return x_stacking;
 }
 
diff --git a/layershellv1client.h b/layershellv1client.h
index 7c3e0cceb..8769a4145 100644
--- a/layershellv1client.h
+++ b/layershellv1client.h
@@ -47,6 +47,7 @@ public:
 protected:
     Layer belongsToLayer() const override;
     bool acceptsFocus() const override;
+    bool shouldUnredirect() const override { return false; }
     void requestGeometry(const QRect &rect) override;
 
 private:
diff --git a/options.cpp b/options.cpp
index 52030f142..fd695c741 100644
--- a/options.cpp
+++ b/options.cpp
@@ -58,6 +58,7 @@ Options::Options(QObject *parent)
     , m_compositingMode(Options::defaultCompositingMode())
     , m_useCompositing(Options::defaultUseCompositing())
     , m_hiddenPreviews(Options::defaultHiddenPreviews())
+    , m_unredirectFullscreen(Options::defaultUnredirectFullscreen())
     , m_glSmoothScale(Options::defaultGlSmoothScale())
     , m_xrenderSmoothScale(Options::defaultXrenderSmoothScale())
     , m_glStrictBinding(Options::defaultGlStrictBinding())
@@ -554,6 +555,20 @@ void Options::setHiddenPreviews(int hiddenPreviews)
     emit hiddenPreviewsChanged();
 }
 
+void Options::setUnredirectFullscreen(bool unredirectFullscreen)
+{
+    //if (GLPlatform::instance()->driver() == Driver_Intel)
+        //unredirectFullscreen = false; // bug #252817
+    if (m_unredirectFullscreen == unredirectFullscreen) {
+        return;
+    }
+    //if (GLPlatform::instance()->driver() == Driver_Intel) { // write back the value
+        //KConfigGroup(m_settings->config(), "Compositing").writeEntry("UnredirectFullscreen", false);
+    //}
+    m_unredirectFullscreen = unredirectFullscreen;
+    emit unredirectFullscreenChanged();
+}
+
 void Options::setGlSmoothScale(int glSmoothScale)
 {
     if (m_glSmoothScale == glSmoothScale) {
@@ -911,6 +926,8 @@ void Options::reloadCompositingSettings(bool force)
     else if (hps == 6)
         previews = HiddenPreviewsAlways;
     setHiddenPreviews(previews);
+
+    setUnredirectFullscreen(config.readEntry("UnredirectFullscreen",Options::defaultUnredirectFullscreen()));
 
     auto interfaceToKey = [](OpenGLPlatformInterface interface) {
         switch (interface) {
@@ -1062,4 +1079,9 @@ bool Options::isUseCompositing() const
     return m_useCompositing || kwinApp()->platform()->requiresCompositing();
 }
 
+bool Options::isUnredirectFullscreen() const
+{
+    return m_unredirectFullscreen && !kwinApp()->platform()->requiresCompositing();
+}
+
 } // namespace
diff --git a/options.h b/options.h
index e692a676e..262314259 100644
--- a/options.h
+++ b/options.h
@@ -179,6 +179,7 @@ class KWIN_EXPORT Options : public QObject
     Q_PROPERTY(int compositingMode READ compositingMode WRITE setCompositingMode NOTIFY compositingModeChanged)
     Q_PROPERTY(bool useCompositing READ isUseCompositing WRITE setUseCompositing NOTIFY useCompositingChanged)
     Q_PROPERTY(int hiddenPreviews READ hiddenPreviews WRITE setHiddenPreviews NOTIFY hiddenPreviewsChanged)
+    Q_PROPERTY(bool unredirectFullscreen READ isUnredirectFullscreen WRITE setUnredirectFullscreen NOTIFY unredirectFullscreenChanged)
     /**
      * 0 = no, 1 = yes when transformed,
      * 2 = try trilinear when transformed; else 1,
@@ -564,6 +565,7 @@ public:
     HiddenPreviews hiddenPreviews() const {
         return m_hiddenPreviews;
     }
+    bool isUnredirectFullscreen() const;
     // OpenGL
     // 0 = no, 1 = yes when transformed,
     // 2 = try trilinear when transformed; else 1,
@@ -657,6 +659,7 @@ public:
     void setCompositingMode(int compositingMode);
     void setUseCompositing(bool useCompositing);
     void setHiddenPreviews(int hiddenPreviews);
+    void setUnredirectFullscreen(bool unredirectFullscreen);
     void setGlSmoothScale(int glSmoothScale);
     void setXrenderSmoothScale(bool xrenderSmoothScale);
     void setGlStrictBinding(bool glStrictBinding);
@@ -739,6 +742,9 @@ public:
     static HiddenPreviews defaultHiddenPreviews() {
         return HiddenPreviewsShown;
     }
+    static bool defaultUnredirectFullscreen() {
+        return true;
+    }
     static int defaultGlSmoothScale() {
         return 2;
     }
@@ -833,6 +839,7 @@ Q_SIGNALS:
     void compositingModeChanged();
     void useCompositingChanged();
     void hiddenPreviewsChanged();
+    void unredirectFullscreenChanged();
     void glSmoothScaleChanged();
     void xrenderSmoothScaleChanged();
     void glStrictBindingChanged();
@@ -878,6 +885,7 @@ private:
     CompositingType m_compositingMode;
     bool m_useCompositing;
     HiddenPreviews m_hiddenPreviews;
+    bool m_unredirectFullscreen;
     int m_glSmoothScale;
     bool m_xrenderSmoothScale;
     // Settings that should be auto-detected
diff --git a/rules.cpp b/rules.cpp
index a75b7775d..97dddfa71 100644
--- a/rules.cpp
+++ b/rules.cpp
@@ -64,6 +64,7 @@ Rules::Rules()
     , noborderrule(UnusedSetRule)
     , decocolorrule(UnusedForceRule)
     , blockcompositingrule(UnusedForceRule)
+    , allowunredirectrule(UnusedForceRule)
     , fsplevelrule(UnusedForceRule)
     , fpplevelrule(UnusedForceRule)
     , acceptfocusrule(UnusedForceRule)
@@ -162,6 +163,7 @@ void Rules::readFromSettings(const RuleSettings *settings)
         decocolorrule = UnusedForceRule;
 
     READ_FORCE_RULE(blockcompositing,);
+    READ_FORCE_RULE(allowunredirect,);
     READ_FORCE_RULE(fsplevel,);
     READ_FORCE_RULE(fpplevel,);
     READ_FORCE_RULE(acceptfocus,);
@@ -243,6 +245,7 @@ void Rules::write(RuleSettings *settings) const
     };
     WRITE_FORCE_RULE(decocolor, Decocolor, colorToString);
     WRITE_FORCE_RULE(blockcompositing, Blockcompositing,);
+    WRITE_FORCE_RULE(allowunredirect, Allowunredirect,);
     WRITE_FORCE_RULE(fsplevel, Fsplevel,);
     WRITE_FORCE_RULE(fpplevel, Fpplevel,);
     WRITE_FORCE_RULE(acceptfocus, Acceptfocus,);
@@ -288,6 +291,7 @@ bool Rules::isEmpty() const
            && noborderrule == UnusedSetRule
            && decocolorrule == UnusedForceRule
            && blockcompositingrule == UnusedForceRule
+           && allowunredirectrule == UnusedForceRule
            && fsplevelrule == UnusedForceRule
            && fpplevelrule == UnusedForceRule
            && acceptfocusrule == UnusedForceRule
@@ -602,6 +606,7 @@ APPLY_RULE(fullscreen, FullScreen, bool)
 APPLY_RULE(noborder, NoBorder, bool)
 APPLY_FORCE_RULE(decocolor, DecoColor, QString)
 APPLY_FORCE_RULE(blockcompositing, BlockCompositing, bool)
+APPLY_FORCE_RULE(allowunredirect, AllowUnredirect, bool)
 APPLY_FORCE_RULE(fsplevel, FSP, int)
 APPLY_FORCE_RULE(fpplevel, FPP, int)
 APPLY_FORCE_RULE(acceptfocus, AcceptFocus, bool)
@@ -677,6 +682,7 @@ bool Rules::discardUsed(bool withdrawn)
     DISCARD_USED_SET_RULE(noborder);
     DISCARD_USED_FORCE_RULE(decocolor);
     DISCARD_USED_FORCE_RULE(blockcompositing);
+    DISCARD_USED_FORCE_RULE(allowunredirect);
     DISCARD_USED_FORCE_RULE(fsplevel);
     DISCARD_USED_FORCE_RULE(fpplevel);
     DISCARD_USED_FORCE_RULE(acceptfocus);
@@ -814,6 +820,7 @@ CHECK_RULE(FullScreen, bool)
 CHECK_RULE(NoBorder, bool)
 CHECK_FORCE_RULE(DecoColor, QString)
 CHECK_FORCE_RULE(BlockCompositing, bool)
+CHECK_FORCE_RULE(AllowUnredirect, bool)
 CHECK_FORCE_RULE(FSP, int)
 CHECK_FORCE_RULE(FPP, int)
 CHECK_FORCE_RULE(AcceptFocus, bool)
diff --git a/rules.h b/rules.h
index 7ffa0789f..b63a6ca75 100644
--- a/rules.h
+++ b/rules.h
@@ -67,6 +67,7 @@ public:
     bool checkNoBorder(bool noborder, bool init = false) const;
     QString checkDecoColor(QString schemeFile) const;
     bool checkBlockCompositing(bool block) const;
+    bool checkAllowUnredirect(bool allow) const;
     int checkFSP(int fsp) const;
     int checkFPP(int fpp) const;
     bool checkAcceptFocus(bool focus) const;
@@ -162,6 +163,7 @@ public:
     bool applyNoBorder(bool& noborder, bool init) const;
     bool applyDecoColor(QString &schemeFile) const;
     bool applyBlockCompositing(bool& block) const;
+    bool applyAllowUnredirect(bool& allow) const;
     bool applyFSP(int& fsp) const;
     bool applyFPP(int& fpp) const;
     bool applyAcceptFocus(bool& focus) const;
@@ -251,6 +253,8 @@ private:
     ForceRule decocolorrule;
     bool blockcompositing;
     ForceRule blockcompositingrule;
+    bool allowunredirect;
+    ForceRule allowunredirectrule;
     int fsplevel;
     int fpplevel;
     ForceRule fsplevelrule;
diff --git a/rulesettings.kcfg b/rulesettings.kcfg
index 0cb10da7e..02cab1487 100644
--- a/rulesettings.kcfg
+++ b/rulesettings.kcfg
@@ -328,6 +328,15 @@
       <default code="true">Rules::UnusedForceRule</default>
     </entry>
 
+    <entry name="allowunredirect" type="Bool">
+      <label>Full-screen unredirection</label>
+      <default>false</default>
+    </entry>
+    <entry name="allowunredirectrule" type="Int">
+      <label>Full-screen unredirection rule type</label>
+      <default code="true">Rules::UnusedForceRule</default>
+    </entry>
+
     <entry name="fsplevel" type="Int">
       <label>Focus stealing prevention</label>
       <default>0</default>
diff --git a/toplevel.cpp b/toplevel.cpp
index b85b6e689..836cc98cc 100644
--- a/toplevel.cpp
+++ b/toplevel.cpp
@@ -25,6 +25,8 @@
 
 #include <QDebug>
 
+#include <unistd.h>
+
 namespace KWin
 {
 
@@ -291,6 +293,7 @@ bool Toplevel::setupCompositing()
     effect_window = new EffectWindowImpl(this);
 
     Compositor::self()->scene()->addToplevel(this);
+    Compositor::self()->checkUnredirect(true);
 
     return true;
 }
@@ -299,6 +302,7 @@ void Toplevel::finishCompositing(ReleaseReason releaseReason)
 {
     if (kwinApp()->operationMode() == Application::OperationModeX11 && damage_handle == XCB_NONE)
         return;
+    Compositor::self()->checkUnredirect(true);
     if (effect_window->window() == this) { // otherwise it's already passed to Deleted, don't free data
         discardWindowPixmap();
         delete effect_window;
@@ -827,5 +831,45 @@ QMargins Toplevel::frameMargins() const
     return QMargins();
 }
 
+bool Toplevel::updateUnredirectedState()
+{
+    assert(compositing());
+    bool should = options->isUnredirectFullscreen() && shouldUnredirect() && !unredirectSuspend &&
+                  !shape() && !hasAlpha() && opacity() == 1.0 &&
+                  !static_cast<EffectsHandlerImpl*>(effects)->activeFullScreenEffect();
+    if (should) {
+      if (Screens::self()->count()<2) {
+        usleep(50000);
+      }
+    }
+    if (should == unredirect)
+        return false;
+    static QElapsedTimer lastUnredirect;
+    static const qint64 msecRedirectInterval = 100;
+    if (!lastUnredirect.hasExpired(msecRedirectInterval)) {
+        QTimer::singleShot(msecRedirectInterval, Compositor::self(), static_cast<void (Compositor::*)()>(&Compositor::checkUnredirect));
+        return false;
+    }
+    lastUnredirect.start();
+    unredirect = should;
+    if (unredirect) {
+        qCDebug(KWIN_CORE) << "Unredirecting:" << this;
+        xcb_composite_unredirect_window(connection(), frameId(), XCB_COMPOSITE_REDIRECT_MANUAL);
+    } else {
+        qCDebug(KWIN_CORE) << "Redirecting:" << this;
+        xcb_composite_redirect_window(connection(), frameId(), XCB_COMPOSITE_REDIRECT_MANUAL);
+        discardWindowPixmap();
+    }
+    return true;
+}
+
+void Toplevel::suspendUnredirect(bool suspend)
+{
+    if (unredirectSuspend == suspend)
+        return;
+    unredirectSuspend = suspend;
+    Compositor::self()->checkUnredirect();
+}
+
 } // namespace
 
diff --git a/toplevel.h b/toplevel.h
index 572bef0e7..e5a52a712 100644
--- a/toplevel.h
+++ b/toplevel.h
@@ -454,6 +454,9 @@ public:
     bool hasAlpha() const;
     virtual bool setupCompositing();
     virtual void finishCompositing(ReleaseReason releaseReason = ReleaseReason::Release);
+    bool updateUnredirectedState();
+    bool unredirected() const;
+    void suspendUnredirect(bool suspend);
     Q_INVOKABLE void addRepaint(const QRect& r);
     Q_INVOKABLE void addRepaint(const QRegion& r);
     Q_INVOKABLE void addRepaint(int x, int y, int w, int h);
@@ -719,6 +722,7 @@ protected:
     void copyToDeleted(Toplevel* c);
     void disownDataPassedToDeleted();
     void deleteEffectWindow();
+    virtual bool shouldUnredirect() const = 0;
     void setDepth(int depth);
     QRect m_frameGeometry;
     QRect m_clientGeometry;
@@ -747,6 +751,8 @@ private:
     QByteArray resource_class;
     ClientMachine *m_clientMachine;
     xcb_window_t m_wmClientLeader;
+    bool unredirect;
+    bool unredirectSuspend; // when unredirected, but pixmap is needed temporarily
     bool m_damageReplyPending;
     QRegion opaque_region;
     xcb_xfixes_fetch_region_cookie_t m_regionCookie;
@@ -1005,6 +1011,11 @@ inline QByteArray Toplevel::resourceClass() const
     return resource_class; // it is always lowercase
 }
 
+inline bool Toplevel::unredirected() const
+{
+    return unredirect;
+}
+
 inline const ClientMachine *Toplevel::clientMachine() const
 {
     return m_clientMachine;
diff --git a/unmanaged.cpp b/unmanaged.cpp
index 3e9a0e0c7..a12e5d068 100644
--- a/unmanaged.cpp
+++ b/unmanaged.cpp
@@ -189,5 +189,35 @@ bool Unmanaged::setupCompositing()
     return true;
 }
 
+bool Unmanaged::shouldUnredirect() const
+{
+    // the pixmap is needed for the login effect, a nicer solution would be the login effect increasing
+    // refcount for the window pixmap (which would prevent unredirect), avoiding this hack
+    if (resourceClass() == "ksplashx"
+            || resourceClass() == "ksplashsimple"
+            || resourceClass() == "ksplashqml"
+            )
+        return false;
+    // it must cover whole display or one xinerama screen, and be the topmost there
+    const int desktop = VirtualDesktopManager::self()->current();
+    // TODO: this mess o-o
+    if (frameGeometry() == workspace()->clientArea(FullArea, frameGeometry().center(), desktop)
+            || frameGeometry() == workspace()->clientArea(ScreenArea, frameGeometry().center(), desktop)) {
+        QList<Toplevel*> stacking = workspace()->xStackingOrder();
+        for (int pos = stacking.count() - 1;
+                pos >= 0;
+                --pos) {
+            Toplevel* c = stacking.at(pos);
+            if (c == this)   // is not covered by any other window, ok to unredirect
+                return true;
+            // TODO: check if this works
+            if (c->frameGeometry().intersects(bufferGeometry()))
+                return false;
+        }
+        abort();
+    }
+    return false;
+}
+
 } // namespace
 
diff --git a/unmanaged.h b/unmanaged.h
index bb8d2a20b..0716cef9a 100644
--- a/unmanaged.h
+++ b/unmanaged.h
@@ -43,6 +43,9 @@ public:
 public Q_SLOTS:
     void release(ReleaseReason releaseReason = ReleaseReason::Release);
 
+ protected:
+    bool shouldUnredirect() const override;
+
 private:
     ~Unmanaged() override; // use release()
     // handlers for X11 events
diff --git a/workspace.cpp b/workspace.cpp
index d701525b6..d95cb8b58 100644
--- a/workspace.cpp
+++ b/workspace.cpp
@@ -552,6 +552,11 @@ X11Client *Workspace::createClient(xcb_window_t w, bool is_mapped)
         connect(c, &X11Client::blockingCompositingChanged, compositor, &X11Compositor::updateClientCompositeBlocking);
     }
     connect(c, &X11Client::clientFullScreenSet, ScreenEdges::self(), &ScreenEdges::checkBlocking);
+    connect(c, &X11Client::activeChanged, m_compositor, static_cast<void (Compositor::*)()>(&Compositor::checkUnredirect));
+    // THIS ONE PLEASE
+    connect(c, &X11Client::fullScreenChanged, m_compositor, static_cast<void (Compositor::*)()>(&Compositor::checkUnredirect));
+    connect(c, &X11Client::geometryChanged, m_compositor, static_cast<void (Compositor::*)()>(&Compositor::checkUnredirect));
+    connect(c, &X11Client::geometryShapeChanged, m_compositor, static_cast<void (Compositor::*)()>(&Compositor::checkUnredirect));
     if (!c->manage(w, is_mapped)) {
         X11Client::deleteClient(c);
         return nullptr;
@@ -1985,6 +1990,9 @@ void Workspace::desktopResized()
     if (effects) {
         static_cast<EffectsHandlerImpl*>(effects)->desktopResized(geom.size());
     }
+
+    // best guess.
+    m_compositor->checkUnredirect(true);
 }
 
 void Workspace::saveOldScreenSizes()
diff --git a/x11client.cpp b/x11client.cpp
index 960fc24c4..68f72d5a2 100644
--- a/x11client.cpp
+++ b/x11client.cpp
@@ -1596,6 +1596,9 @@ void X11Client::internalShow()
         m_decoInputExtent.map();
         updateHiddenPreview();
     }
+    if (Compositor::self()->isActive()) {
+        Compositor::self()->checkUnredirect();
+    }
     emit windowShown(this);
 }
 
@@ -1611,6 +1614,9 @@ void X11Client::internalHide()
         updateHiddenPreview();
     addWorkspaceRepaint(visibleRect());
     workspace()->clientHidden(this);
+    if (Compositor::self()->isActive()) {
+        Compositor::self()->checkUnredirect();
+    }
     emit windowHidden(this);
 }
 
@@ -1629,6 +1635,9 @@ void X11Client::internalKeep()
     updateHiddenPreview();
     addWorkspaceRepaint(visibleRect());
     workspace()->clientHidden(this);
+    if (Compositor::self()->isActive()) {
+        Compositor::self()->checkUnredirect();
+    }
 }
 
 /**
@@ -2896,6 +2905,10 @@ void X11Client::move(int x, int y, ForceGeometry_t force)
     updateGeometryBeforeUpdateBlocking();
     screens()->setCurrent(this);
     workspace()->updateStackingOrder();
+    if (Compositor::self()->isActive()) {
+        // TODO: there was a todo here but I don't know
+        Compositor::self()->checkUnredirect();
+    }
     // client itself is not damaged
     if (oldBufferGeometry != bufferGeometry()) {
         emit bufferGeometryChanged(this, oldBufferGeometry);
@@ -4920,4 +4933,35 @@ void X11Client::updateWindowPixmap()
     }
 }
 
+// TODO THIS
+bool X11Client::shouldUnredirect() const
+{
+    if (isActiveFullScreen()) {
+        if (!rules()->checkAllowUnredirect(true)) return false;
+        QList<Toplevel*> stacking = workspace()->xStackingOrder();
+        for (int pos = stacking.count() - 1;
+                pos >= 0;
+                --pos) {
+            Toplevel* c = stacking.at(pos);
+            if (c == this) {   // is not covered by any other window, ok to unredirect
+                //printf("yes.\n");
+                return true;
+            }
+            if (c->frameGeometry().intersects(frameGeometry())) {
+                // check whether this is an invisible floating icon at the top left corner
+                if (c->frameGeometry()==QRect(0,0,32,32)) {
+                  //printf("yes via hack.\n");
+                  return true;
+                }
+                //printf("no. this: %d %d %d %d. other: %d %d %d %d.\n",geometry().x(),geometry().y(),geometry().width(),geometry().height(),c->geometry().x(),c->geometry().y(),c->geometry().width(),c->geometry().height());
+                return false;
+            }
+        }
+        //printf("ABORT\n");
+        abort();
+    }
+    return false;
+}
+
+
 } // namespace
diff --git a/x11client.h b/x11client.h
index d3081bba5..9f62326e5 100644
--- a/x11client.h
+++ b/x11client.h
@@ -317,6 +317,7 @@ private:
     bool motionNotifyEvent(xcb_window_t w, int state, int x, int y, int x_root, int y_root);
 
 protected:
+    bool shouldUnredirect() const override;
     void addDamage(const QRegion &damage) override;
     bool belongsToSameApplication(const AbstractClient *other, SameApplicationChecks checks) const override;
     void doSetActive() override;
diff --git a/xdgshellclient.h b/xdgshellclient.h
index 7d783fdf6..d0cf9f33a 100644
--- a/xdgshellclient.h
+++ b/xdgshellclient.h
@@ -63,6 +63,7 @@ public:
     virtual void installPlasmaShellSurface(KWaylandServer::PlasmaShellSurfaceInterface *shellSurface) = 0;
 
 protected:
+    bool shouldUnredirect() const override { return false; }
     void requestGeometry(const QRect &rect) override;
 
     virtual XdgSurfaceConfigure *sendRoleConfigure() const = 0;