diff --git a/effects/wobblywindows/wobblywindows.cpp b/effects/wobblywindows/wobblywindows.cpp
index aa0d6e83e..4abfe682a 100644
--- a/effects/wobblywindows/wobblywindows.cpp
+++ b/effects/wobblywindows/wobblywindows.cpp
@@ -1,1090 +1,1094 @@
 /*****************************************************************
  KWin - the KDE window manager
  This file is part of the KDE project.
 
 Copyright (C) 2008 Cédric Borgese <cedric.borgese@gmail.com>
 
 You can Freely distribute this program under the GNU General Public
 License. See the file "COPYING" for the exact licensing terms.
 ******************************************************************/
 
 
 #include "wobblywindows.h"
 #include "wobblywindowsconfig.h"
 
 #include <cmath>
 
 //#define COMPUTE_STATS
 
 // if you enable it and run kwin in a terminal from the session it manages,
 // be sure to redirect the output of kwin in a file or
 // you'll propably get deadlocks.
 //#define VERBOSE_MODE
 
 #if defined COMPUTE_STATS && !defined VERBOSE_MODE
 #   ifdef __GNUC__
 #       warning "You enable COMPUTE_STATS without VERBOSE_MODE, computed stats will not be printed."
 #   endif
 #endif
 
 namespace KWin
 {
 
 struct ParameterSet {
     qreal stiffness;
     qreal drag;
     qreal move_factor;
 
     qreal xTesselation;
     qreal yTesselation;
 
     qreal minVelocity;
     qreal maxVelocity;
     qreal stopVelocity;
     qreal minAcceleration;
     qreal maxAcceleration;
     qreal stopAcceleration;
 };
 
 static const ParameterSet set_0 = {
     0.15,
     0.80,
     0.10,
     20.0,
     20.0,
     0.0,
     1000.0,
     0.5,
     0.0,
     1000.0,
     0.5,
 };
 
 static const ParameterSet set_1 = {
     0.10,
     0.85,
     0.10,
     20.0,
     20.0,
     0.0,
     1000.0,
     0.5,
     0.0,
     1000.0,
     0.5,
 };
 
 static const ParameterSet set_2 = {
     0.06,
     0.90,
     0.10,
     20.0,
     20.0,
     0.0,
     1000.0,
     0.5,
     0.0,
     1000.0,
     0.5,
 };
 
 static const ParameterSet set_3 = {
     0.03,
     0.92,
     0.20,
     20.0,
     20.0,
     0.0,
     1000.0,
     0.5,
     0.0,
     1000.0,
     0.5,
 };
 
 static const ParameterSet set_4 = {
     0.01,
     0.97,
     0.25,
     20.0,
     20.0,
     0.0,
     1000.0,
     0.5,
     0.0,
     1000.0,
     0.5,
 };
 
 static const ParameterSet pset[5] = { set_0, set_1, set_2, set_3, set_4 };
 
 WobblyWindowsEffect::WobblyWindowsEffect()
 {
     initConfig<WobblyWindowsConfig>();
     reconfigure(ReconfigureAll);
     connect(effects, &EffectsHandler::windowStartUserMovedResized, this, &WobblyWindowsEffect::slotWindowStartUserMovedResized);
     connect(effects, &EffectsHandler::windowStepUserMovedResized, this, &WobblyWindowsEffect::slotWindowStepUserMovedResized);
     connect(effects, &EffectsHandler::windowFinishUserMovedResized, this, &WobblyWindowsEffect::slotWindowFinishUserMovedResized);
     connect(effects, &EffectsHandler::windowMaximizedStateChanged, this, &WobblyWindowsEffect::slotWindowMaximizeStateChanged);
 }
 
 WobblyWindowsEffect::~WobblyWindowsEffect()
 {
     if (!windows.empty()) {
         // we should be empty at this point...
         // emit a warning and clean the list.
         qCDebug(KWINEFFECTS) << "Windows list not empty. Left items : " << windows.count();
         QHash< const EffectWindow*,  WindowWobblyInfos >::iterator i;
         for (i = windows.begin(); i != windows.end(); ++i) {
             freeWobblyInfo(i.value());
         }
     }
 }
 
 void WobblyWindowsEffect::reconfigure(ReconfigureFlags)
 {
     WobblyWindowsConfig::self()->read();
 
     QString settingsMode = WobblyWindowsConfig::settings();
     if (settingsMode != QStringLiteral("Custom")) {
         unsigned int wobblynessLevel = WobblyWindowsConfig::wobblynessLevel();
         if (wobblynessLevel > 4) {
             qCDebug(KWINEFFECTS) << "Wrong value for \"WobblynessLevel\" : " << wobblynessLevel;
             wobblynessLevel = 4;
         }
         setParameterSet(pset[wobblynessLevel]);
 
         if (WobblyWindowsConfig::advancedMode()) {
             m_stiffness = WobblyWindowsConfig::stiffness() / 100.0;
             m_drag = WobblyWindowsConfig::drag() / 100.0;
             m_move_factor = WobblyWindowsConfig::moveFactor() / 100.0;
         }
     } else { // Custom method, read all values from config file.
         m_stiffness = WobblyWindowsConfig::stiffness() / 100.0;
         m_drag = WobblyWindowsConfig::drag() / 100.0;
         m_move_factor = WobblyWindowsConfig::moveFactor() / 100.0;
 
         m_xTesselation = WobblyWindowsConfig::xTesselation();
         m_yTesselation = WobblyWindowsConfig::yTesselation();
 
         m_minVelocity = WobblyWindowsConfig::minVelocity();
         m_maxVelocity = WobblyWindowsConfig::maxVelocity();
         m_stopVelocity = WobblyWindowsConfig::stopVelocity();
         m_minAcceleration = WobblyWindowsConfig::minAcceleration();
         m_maxAcceleration = WobblyWindowsConfig::maxAcceleration();
         m_stopAcceleration = WobblyWindowsConfig::stopAcceleration();
     }
 
     m_moveWobble = WobblyWindowsConfig::moveWobble();
     m_resizeWobble = WobblyWindowsConfig::resizeWobble();
 
 #if defined VERBOSE_MODE
     qCDebug(KWINEFFECTS) << "Parameters :\n" <<
                  "grid(" << m_stiffness << ", " << m_drag << ", " << m_move_factor << ")\n" <<
                  "velocity(" << m_minVelocity << ", " << m_maxVelocity << ", " << m_stopVelocity << ")\n" <<
                  "acceleration(" << m_minAcceleration << ", " << m_maxAcceleration << ", " << m_stopAcceleration << ")\n" <<
                  "tesselation(" << m_xTesselation <<  ", " << m_yTesselation << ")";
 #endif
 }
 
 bool WobblyWindowsEffect::supported()
 {
     return effects->isOpenGLCompositing() && effects->animationsSupported();
 }
 
 void WobblyWindowsEffect::setParameterSet(const ParameterSet& pset)
 {
     m_stiffness = pset.stiffness;
     m_drag = pset.drag;
     m_move_factor = pset.move_factor;
 
     m_xTesselation = pset.xTesselation;
     m_yTesselation = pset.yTesselation;
 
     m_minVelocity =  pset.minVelocity;
     m_maxVelocity =  pset.maxVelocity;
     m_stopVelocity =  pset.stopVelocity;
     m_minAcceleration =  pset.minAcceleration;
     m_maxAcceleration =  pset.maxAcceleration;
     m_stopAcceleration =  pset.stopAcceleration;
 }
 
 void WobblyWindowsEffect::setVelocityThreshold(qreal m_minVelocity)
 {
     this->m_minVelocity = m_minVelocity;
 }
 
 void WobblyWindowsEffect::setMoveFactor(qreal factor)
 {
     m_move_factor = factor;
 }
 
 void WobblyWindowsEffect::setStiffness(qreal stiffness)
 {
     m_stiffness = stiffness;
 }
 
 void WobblyWindowsEffect::setDrag(qreal drag)
 {
     m_drag = drag;
 }
 
 void WobblyWindowsEffect::prePaintScreen(ScreenPrePaintData& data, int time)
 {
     // We need to mark the screen windows as transformed. Otherwise the whole
     // screen won't be repainted, resulting in artefacts.
     // Could we just set a subset of the screen to be repainted ?
     if (windows.count() != 0) {
         m_updateRegion = QRegion();
     }
 
     effects->prePaintScreen(data, time);
 }
 const qreal maxTime = 10.0;
 void WobblyWindowsEffect::prePaintWindow(EffectWindow* w, WindowPrePaintData& data, int time)
 {
     if (windows.contains(w)) {
         data.setTransformed();
         data.quads = data.quads.makeRegularGrid(m_xTesselation, m_yTesselation);
         bool stop = false;
         qreal updateTime = time;
 
+        // We have to reset the clip region in order to render clients below
+        // opaque wobbly windows.
+        data.clip = QRegion();
+
         while (!stop && (updateTime > maxTime)) {
 #if defined VERBOSE_MODE
             qCDebug(KWINEFFECTS) << "loop time " << updateTime << " / " << time;
 #endif
             stop = !updateWindowWobblyDatas(w, maxTime);
             updateTime -= maxTime;
         }
         if (!stop && updateTime > 0) {
             updateWindowWobblyDatas(w, updateTime);
         }
     }
 
     effects->prePaintWindow(w, data, time);
 }
 
 void WobblyWindowsEffect::paintWindow(EffectWindow* w, int mask, QRegion region, WindowPaintData& data)
 {
     if (!(mask & PAINT_SCREEN_TRANSFORMED) && windows.contains(w)) {
         WindowWobblyInfos& wwi = windows[w];
         int tx = w->geometry().x();
         int ty = w->geometry().y();
         double left = 0.0;
         double top = 0.0;
         double right = w->width();
         double bottom = w->height();
         for (int i = 0; i < data.quads.count(); ++i) {
             for (int j = 0; j < 4; ++j) {
                 WindowVertex& v = data.quads[i][j];
                 Pair oldPos = {tx + v.x(), ty + v.y()};
                 Pair newPos = computeBezierPoint(wwi, oldPos);
                 v.move(newPos.x - tx, newPos.y - ty);
             }
             left   = qMin(left,   data.quads[i].left());
             top    = qMin(top,    data.quads[i].top());
             right  = qMax(right,  data.quads[i].right());
             bottom = qMax(bottom, data.quads[i].bottom());
         }
         QRectF dirtyRect(
             left * data.xScale() + w->x() + data.xTranslation(),
             top * data.yScale() + w->y() + data.yTranslation(),
             (right - left + 1.0) * data.xScale(),
             (bottom - top + 1.0) * data.yScale());
         // Expand the dirty region by 1px to fix potential round/floor issues.
         dirtyRect.adjust(-1.0, -1.0, 1.0, 1.0);
         m_updateRegion = m_updateRegion.united(dirtyRect.toRect());
     }
 
     // Call the next effect.
     effects->paintWindow(w, mask, region, data);
 }
 
 void WobblyWindowsEffect::postPaintScreen()
 {
     if (!windows.isEmpty()) {
         effects->addRepaint(m_updateRegion);
     }
 
     // Call the next effect.
     effects->postPaintScreen();
 }
 
 void WobblyWindowsEffect::slotWindowStartUserMovedResized(EffectWindow *w)
 {
     if (w->isSpecialWindow()) {
         return;
     }
 
     if ((w->isUserMove() && m_moveWobble) || (w->isUserResize() && m_resizeWobble)) {
         startMovedResized(w);
     }
 }
 
 void WobblyWindowsEffect::slotWindowStepUserMovedResized(EffectWindow *w, const QRect &geometry)
 {
     Q_UNUSED(geometry)
     if (windows.contains(w)) {
         WindowWobblyInfos& wwi = windows[w];
         QRect rect = w->geometry();
         if (rect.y() != wwi.resize_original_rect.y()) wwi.can_wobble_top = true;
         if (rect.x() != wwi.resize_original_rect.x()) wwi.can_wobble_left = true;
         if (rect.right() != wwi.resize_original_rect.right()) wwi.can_wobble_right = true;
         if (rect.bottom() != wwi.resize_original_rect.bottom()) wwi.can_wobble_bottom = true;
     }
 }
 
 void WobblyWindowsEffect::slotWindowFinishUserMovedResized(EffectWindow *w)
 {
     if (windows.contains(w)) {
         WindowWobblyInfos& wwi = windows[w];
         wwi.status = Free;
         QRect rect = w->geometry();
         if (rect.y() != wwi.resize_original_rect.y()) wwi.can_wobble_top = true;
         if (rect.x() != wwi.resize_original_rect.x()) wwi.can_wobble_left = true;
         if (rect.right() != wwi.resize_original_rect.right()) wwi.can_wobble_right = true;
         if (rect.bottom() != wwi.resize_original_rect.bottom()) wwi.can_wobble_bottom = true;
     }
 }
 
 void WobblyWindowsEffect::slotWindowMaximizeStateChanged(EffectWindow *w, bool horizontal, bool vertical)
 {
     Q_UNUSED(horizontal)
     Q_UNUSED(vertical)
     if (w->isUserMove() || w->isSpecialWindow()) {
         return;
     }
 
     if (m_moveWobble && m_resizeWobble) {
         stepMovedResized(w);
     }
 
     if (windows.contains(w)) {
         WindowWobblyInfos& wwi = windows[w];
         QRect rect = w->geometry();
         if (rect.y() != wwi.resize_original_rect.y()) wwi.can_wobble_top = true;
         if (rect.x() != wwi.resize_original_rect.x()) wwi.can_wobble_left = true;
         if (rect.right() != wwi.resize_original_rect.right()) wwi.can_wobble_right = true;
         if (rect.bottom() != wwi.resize_original_rect.bottom()) wwi.can_wobble_bottom = true;
     }
 }
 
 void WobblyWindowsEffect::startMovedResized(EffectWindow* w)
 {
     if (!windows.contains(w)) {
         WindowWobblyInfos new_wwi;
         initWobblyInfo(new_wwi, w->geometry());
         windows[w] = new_wwi;
     }
 
     WindowWobblyInfos& wwi = windows[w];
     wwi.status = Moving;
     const QRectF& rect = w->geometry();
 
     qreal x_increment = rect.width() / (wwi.width - 1.0);
     qreal y_increment = rect.height() / (wwi.height - 1.0);
 
     Pair picked = {static_cast<qreal>(cursorPos().x()), static_cast<qreal>(cursorPos().y())};
     int indx = (picked.x - rect.x()) / x_increment + 0.5;
     int indy = (picked.y - rect.y()) / y_increment + 0.5;
     int pickedPointIndex = indy * wwi.width + indx;
     if (pickedPointIndex < 0) {
         qCDebug(KWINEFFECTS) << "Picked index == " << pickedPointIndex << " with (" << cursorPos().x() << "," << cursorPos().y() << ")";
         pickedPointIndex = 0;
     } else if (static_cast<unsigned int>(pickedPointIndex) > wwi.count - 1) {
         qCDebug(KWINEFFECTS) << "Picked index == " << pickedPointIndex << " with (" << cursorPos().x() << "," << cursorPos().y() << ")";
         pickedPointIndex = wwi.count - 1;
     }
 #if defined VERBOSE_MODE
     qCDebug(KWINEFFECTS) << "Original Picked point -- x : " << picked.x << " - y : " << picked.y;
 #endif
     wwi.constraint[pickedPointIndex] = true;
 
     if (w->isUserResize()) {
         // on a resize, do not allow any edges to wobble until it has been moved from
         // its original location
         wwi.can_wobble_top = wwi.can_wobble_left = wwi.can_wobble_right = wwi.can_wobble_bottom = false;
         wwi.resize_original_rect = w->geometry();
     } else {
         wwi.can_wobble_top = wwi.can_wobble_left = wwi.can_wobble_right = wwi.can_wobble_bottom = true;
     }
 }
 
 void WobblyWindowsEffect::stepMovedResized(EffectWindow* w)
 {
     QRect new_geometry = w->geometry();
     if (!windows.contains(w)) {
         WindowWobblyInfos new_wwi;
         initWobblyInfo(new_wwi, new_geometry);
         windows[w] = new_wwi;
     }
 
     WindowWobblyInfos& wwi = windows[w];
     wwi.status = Free;
 
     QRect maximized_area = effects->clientArea(MaximizeArea, w);
     bool throb_direction_out = (new_geometry.top() == maximized_area.top() && new_geometry.bottom() == maximized_area.bottom()) ||
                                (new_geometry.left() == maximized_area.left() && new_geometry.right() == maximized_area.right());
     qreal magnitude = throb_direction_out ? 10 : -30; // a small throb out when maximized, a larger throb inwards when restored
     for (unsigned int j = 0; j < wwi.height; ++j) {
         for (unsigned int i = 0; i < wwi.width; ++i) {
             Pair v = { magnitude*(i / qreal(wwi.width - 1) - 0.5), magnitude*(j / qreal(wwi.height - 1) - 0.5) };
             wwi.velocity[j*wwi.width+i] = v;
         }
     }
 
     // constrain the middle of the window, so that any asymetry wont cause it to drift off-center
     for (unsigned int j = 1; j < wwi.height - 1; ++j) {
         for (unsigned int i = 1; i < wwi.width - 1; ++i) {
             wwi.constraint[j*wwi.width+i] = true;
         }
     }
 }
 
 void WobblyWindowsEffect::initWobblyInfo(WindowWobblyInfos& wwi, QRect geometry) const
 {
     wwi.count = 4 * 4;
     wwi.width = 4;
     wwi.height = 4;
 
     wwi.bezierWidth = m_xTesselation;
     wwi.bezierHeight = m_yTesselation;
     wwi.bezierCount = m_xTesselation * m_yTesselation;
 
     wwi.origin = new Pair[wwi.count];
     wwi.position = new Pair[wwi.count];
     wwi.velocity = new Pair[wwi.count];
     wwi.acceleration = new Pair[wwi.count];
     wwi.buffer = new Pair[wwi.count];
     wwi.constraint = new bool[wwi.count];
 
     wwi.bezierSurface = new Pair[wwi.bezierCount];
 
     wwi.status = Moving;
 
     qreal x = geometry.x(), y = geometry.y();
     qreal width = geometry.width(), height = geometry.height();
 
     Pair initValue = {x, y};
     static const Pair nullPair = {0.0, 0.0};
 
     qreal x_increment = width / (wwi.width - 1.0);
     qreal y_increment = height / (wwi.height - 1.0);
 
     for (unsigned int j = 0; j < 4; ++j) {
         for (unsigned int i = 0; i < 4; ++i) {
             unsigned int idx = j * 4 + i;
             wwi.origin[idx] = initValue;
             wwi.position[idx] = initValue;
             wwi.velocity[idx] = nullPair;
             wwi.constraint[idx] = false;
             if (i != 4 - 2) { // x grid count - 2, i.e. not the last point
                 initValue.x += x_increment;
             } else {
                 initValue.x = width + x;
             }
             initValue.x = initValue.x;
         }
         initValue.x = x;
         initValue.x = initValue.x;
         if (j != 4 - 2) { // y grid count - 2, i.e. not the last point
             initValue.y += y_increment;
         } else {
             initValue.y = height + y;
         }
         initValue.y = initValue.y;
     }
 }
 
 void WobblyWindowsEffect::freeWobblyInfo(WindowWobblyInfos& wwi) const
 {
     delete[] wwi.origin;
     delete[] wwi.position;
     delete[] wwi.velocity;
     delete[] wwi.acceleration;
     delete[] wwi.buffer;
     delete[] wwi.constraint;
 
     delete[] wwi.bezierSurface;
 }
 
 WobblyWindowsEffect::Pair WobblyWindowsEffect::computeBezierPoint(const WindowWobblyInfos& wwi, Pair point) const
 {
     // compute the input value
     Pair topleft = wwi.origin[0];
     Pair bottomright = wwi.origin[wwi.count-1];
 
     qreal tx = (point.x - topleft.x) / (bottomright.x - topleft.x);
     qreal ty = (point.y - topleft.y) / (bottomright.y - topleft.y);
 
     // compute polynomial coeff
 
     qreal px[4];
     px[0] = (1 - tx) * (1 - tx) * (1 - tx);
     px[1] = 3 * (1 - tx) * (1 - tx) * tx;
     px[2] = 3 * (1 - tx) * tx * tx;
     px[3] = tx * tx * tx;
 
     qreal py[4];
     py[0] = (1 - ty) * (1 - ty) * (1 - ty);
     py[1] = 3 * (1 - ty) * (1 - ty) * ty;
     py[2] = 3 * (1 - ty) * ty * ty;
     py[3] = ty * ty * ty;
 
     Pair res = {0.0, 0.0};
 
     for (unsigned int j = 0; j < 4; ++j) {
         for (unsigned int i = 0; i < 4; ++i) {
             // this assume the grid is 4*4
             res.x += px[i] * py[j] * wwi.position[i + j * wwi.width].x;
             res.y += px[i] * py[j] * wwi.position[i + j * wwi.width].y;
         }
     }
 
     return res;
 }
 
 namespace
 {
 
 static inline void fixVectorBounds(WobblyWindowsEffect::Pair& vec, qreal min, qreal max)
 {
     if (fabs(vec.x) < min) {
         vec.x = 0.0;
     } else if (fabs(vec.x) > max) {
         if (vec.x > 0.0) {
             vec.x = max;
         } else {
             vec.x = -max;
         }
     }
 
     if (fabs(vec.y) < min) {
         vec.y = 0.0;
     } else if (fabs(vec.y) > max) {
         if (vec.y > 0.0) {
             vec.y = max;
         } else {
             vec.y = -max;
         }
     }
 }
 
 #if defined COMPUTE_STATS
 static inline void computeVectorBounds(WobblyWindowsEffect::Pair& vec, WobblyWindowsEffect::Pair& bound)
 {
     if (fabs(vec.x) < bound.x) {
         bound.x = fabs(vec.x);
     } else if (fabs(vec.x) > bound.y) {
         bound.y = fabs(vec.x);
     }
     if (fabs(vec.y) < bound.x) {
         bound.x = fabs(vec.y);
     } else if (fabs(vec.y) > bound.y) {
         bound.y = fabs(vec.y);
     }
 }
 #endif
 
 } // close the anonymous namespace
 
 bool WobblyWindowsEffect::updateWindowWobblyDatas(EffectWindow* w, qreal time)
 {
     QRectF rect = w->geometry();
     WindowWobblyInfos& wwi = windows[w];
 
     qreal x_length = rect.width() / (wwi.width - 1.0);
     qreal y_length = rect.height() / (wwi.height - 1.0);
 
 #if defined VERBOSE_MODE
     qCDebug(KWINEFFECTS) << "time " << time;
     qCDebug(KWINEFFECTS) << "increment x " << x_length << " // y" <<  y_length;
 #endif
 
     Pair origine = {rect.x(), rect.y()};
 
     for (unsigned int j = 0; j < wwi.height; ++j) {
         for (unsigned int i = 0; i < wwi.width; ++i) {
             wwi.origin[wwi.width*j + i] = origine;
             if (i != wwi.width - 2) {
                 origine.x += x_length;
             } else {
                 origine.x = rect.width() + rect.x();
             }
         }
         origine.x = rect.x();
         if (j != wwi.height - 2) {
             origine.y += y_length;
         } else {
             origine.y = rect.height() + rect.y();
         }
     }
 
     Pair neibourgs[4];
     Pair acceleration;
 
     qreal acc_sum = 0.0;
     qreal vel_sum = 0.0;
 
     // compute acceleration, velocity and position for each point
 
     // for corners
 
     // top-left
 
     if (wwi.constraint[0]) {
         Pair window_pos = wwi.origin[0];
         Pair current_pos = wwi.position[0];
         Pair move = {window_pos.x - current_pos.x, window_pos.y - current_pos.y};
         Pair accel = {move.x*m_stiffness, move.y*m_stiffness};
         wwi.acceleration[0] = accel;
     } else {
         Pair& pos = wwi.position[0];
         neibourgs[0] = wwi.position[1];
         neibourgs[1] = wwi.position[wwi.width];
 
         acceleration.x = ((neibourgs[0].x - pos.x) - x_length) * m_stiffness + (neibourgs[1].x - pos.x) * m_stiffness;
         acceleration.y = ((neibourgs[1].y - pos.y) - y_length) * m_stiffness + (neibourgs[0].y - pos.y) * m_stiffness;
 
         acceleration.x /= 2;
         acceleration.y /= 2;
 
         wwi.acceleration[0] = acceleration;
     }
 
     // top-right
 
     if (wwi.constraint[wwi.width-1]) {
         Pair window_pos = wwi.origin[wwi.width-1];
         Pair current_pos = wwi.position[wwi.width-1];
         Pair move = {window_pos.x - current_pos.x, window_pos.y - current_pos.y};
         Pair accel = {move.x*m_stiffness, move.y*m_stiffness};
         wwi.acceleration[wwi.width-1] = accel;
     } else {
         Pair& pos = wwi.position[wwi.width-1];
         neibourgs[0] = wwi.position[wwi.width-2];
         neibourgs[1] = wwi.position[2*wwi.width-1];
 
         acceleration.x = (x_length - (pos.x - neibourgs[0].x)) * m_stiffness + (neibourgs[1].x - pos.x) * m_stiffness;
         acceleration.y = ((neibourgs[1].y - pos.y) - y_length) * m_stiffness + (neibourgs[0].y - pos.y) * m_stiffness;
 
         acceleration.x /= 2;
         acceleration.y /= 2;
 
         wwi.acceleration[wwi.width-1] = acceleration;
     }
 
     // bottom-left
 
     if (wwi.constraint[wwi.width*(wwi.height-1)]) {
         Pair window_pos = wwi.origin[wwi.width*(wwi.height-1)];
         Pair current_pos = wwi.position[wwi.width*(wwi.height-1)];
         Pair move = {window_pos.x - current_pos.x, window_pos.y - current_pos.y};
         Pair accel = {move.x*m_stiffness, move.y*m_stiffness};
         wwi.acceleration[wwi.width*(wwi.height-1)] = accel;
     } else {
         Pair& pos = wwi.position[wwi.width*(wwi.height-1)];
         neibourgs[0] = wwi.position[wwi.width*(wwi.height-1)+1];
         neibourgs[1] = wwi.position[wwi.width*(wwi.height-2)];
 
         acceleration.x = ((neibourgs[0].x - pos.x) - x_length) * m_stiffness + (neibourgs[1].x - pos.x) * m_stiffness;
         acceleration.y = (y_length - (pos.y - neibourgs[1].y)) * m_stiffness + (neibourgs[0].y - pos.y) * m_stiffness;
 
         acceleration.x /= 2;
         acceleration.y /= 2;
 
         wwi.acceleration[wwi.width*(wwi.height-1)] = acceleration;
     }
 
     // bottom-right
 
     if (wwi.constraint[wwi.count-1]) {
         Pair window_pos = wwi.origin[wwi.count-1];
         Pair current_pos = wwi.position[wwi.count-1];
         Pair move = {window_pos.x - current_pos.x, window_pos.y - current_pos.y};
         Pair accel = {move.x*m_stiffness, move.y*m_stiffness};
         wwi.acceleration[wwi.count-1] = accel;
     } else {
         Pair& pos = wwi.position[wwi.count-1];
         neibourgs[0] = wwi.position[wwi.count-2];
         neibourgs[1] = wwi.position[wwi.width*(wwi.height-1)-1];
 
         acceleration.x = (x_length - (pos.x - neibourgs[0].x)) * m_stiffness + (neibourgs[1].x - pos.x) * m_stiffness;
         acceleration.y = (y_length - (pos.y - neibourgs[1].y)) * m_stiffness + (neibourgs[0].y - pos.y) * m_stiffness;
 
         acceleration.x /= 2;
         acceleration.y /= 2;
 
         wwi.acceleration[wwi.count-1] = acceleration;
     }
 
 
     // for borders
 
     // top border
     for (unsigned int i = 1; i < wwi.width - 1; ++i) {
         if (wwi.constraint[i]) {
             Pair window_pos = wwi.origin[i];
             Pair current_pos = wwi.position[i];
             Pair move = {window_pos.x - current_pos.x, window_pos.y - current_pos.y};
             Pair accel = {move.x*m_stiffness, move.y*m_stiffness};
             wwi.acceleration[i] = accel;
         } else {
             Pair& pos = wwi.position[i];
             neibourgs[0] = wwi.position[i-1];
             neibourgs[1] = wwi.position[i+1];
             neibourgs[2] = wwi.position[i+wwi.width];
 
             acceleration.x = (x_length - (pos.x - neibourgs[0].x)) * m_stiffness + ((neibourgs[1].x - pos.x) - x_length) * m_stiffness + (neibourgs[2].x - pos.x) * m_stiffness;
             acceleration.y = ((neibourgs[2].y - pos.y) - y_length) * m_stiffness + (neibourgs[0].y - pos.y) * m_stiffness + (neibourgs[1].y - pos.y) * m_stiffness;
 
             acceleration.x /= 3;
             acceleration.y /= 3;
 
             wwi.acceleration[i] = acceleration;
         }
     }
 
     // bottom border
     for (unsigned int i = wwi.width * (wwi.height - 1) + 1; i < wwi.count - 1; ++i) {
         if (wwi.constraint[i]) {
             Pair window_pos = wwi.origin[i];
             Pair current_pos = wwi.position[i];
             Pair move = {window_pos.x - current_pos.x, window_pos.y - current_pos.y};
             Pair accel = {move.x*m_stiffness, move.y*m_stiffness};
             wwi.acceleration[i] = accel;
         } else {
             Pair& pos = wwi.position[i];
             neibourgs[0] = wwi.position[i-1];
             neibourgs[1] = wwi.position[i+1];
             neibourgs[2] = wwi.position[i-wwi.width];
 
             acceleration.x = (x_length - (pos.x - neibourgs[0].x)) * m_stiffness + ((neibourgs[1].x - pos.x) - x_length) * m_stiffness + (neibourgs[2].x - pos.x) * m_stiffness;
             acceleration.y = (y_length - (pos.y - neibourgs[2].y)) * m_stiffness + (neibourgs[0].y - pos.y) * m_stiffness + (neibourgs[1].y - pos.y) * m_stiffness;
 
             acceleration.x /= 3;
             acceleration.y /= 3;
 
             wwi.acceleration[i] = acceleration;
         }
     }
 
     // left border
     for (unsigned int i = wwi.width; i < wwi.width*(wwi.height - 1); i += wwi.width) {
         if (wwi.constraint[i]) {
             Pair window_pos = wwi.origin[i];
             Pair current_pos = wwi.position[i];
             Pair move = {window_pos.x - current_pos.x, window_pos.y - current_pos.y};
             Pair accel = {move.x*m_stiffness, move.y*m_stiffness};
             wwi.acceleration[i] = accel;
         } else {
             Pair& pos = wwi.position[i];
             neibourgs[0] = wwi.position[i+1];
             neibourgs[1] = wwi.position[i-wwi.width];
             neibourgs[2] = wwi.position[i+wwi.width];
 
             acceleration.x = ((neibourgs[0].x - pos.x) - x_length) * m_stiffness + (neibourgs[1].x - pos.x) * m_stiffness + (neibourgs[2].x - pos.x) * m_stiffness;
             acceleration.y = (y_length - (pos.y - neibourgs[1].y)) * m_stiffness + ((neibourgs[2].y - pos.y) - y_length) * m_stiffness + (neibourgs[0].y - pos.y) * m_stiffness;
 
             acceleration.x /= 3;
             acceleration.y /= 3;
 
             wwi.acceleration[i] = acceleration;
         }
     }
 
     // right border
     for (unsigned int i = 2 * wwi.width - 1; i < wwi.count - 1; i += wwi.width) {
         if (wwi.constraint[i]) {
             Pair window_pos = wwi.origin[i];
             Pair current_pos = wwi.position[i];
             Pair move = {window_pos.x - current_pos.x, window_pos.y - current_pos.y};
             Pair accel = {move.x*m_stiffness, move.y*m_stiffness};
             wwi.acceleration[i] = accel;
         } else {
             Pair& pos = wwi.position[i];
             neibourgs[0] = wwi.position[i-1];
             neibourgs[1] = wwi.position[i-wwi.width];
             neibourgs[2] = wwi.position[i+wwi.width];
 
             acceleration.x = (x_length - (pos.x - neibourgs[0].x)) * m_stiffness + (neibourgs[1].x - pos.x) * m_stiffness + (neibourgs[2].x - pos.x) * m_stiffness;
             acceleration.y = (y_length - (pos.y - neibourgs[1].y)) * m_stiffness + ((neibourgs[2].y - pos.y) - y_length) * m_stiffness + (neibourgs[0].y - pos.y) * m_stiffness;
 
             acceleration.x /= 3;
             acceleration.y /= 3;
 
             wwi.acceleration[i] = acceleration;
         }
     }
 
     // for the inner points
     for (unsigned int j = 1; j < wwi.height - 1; ++j) {
         for (unsigned int i = 1; i < wwi.width - 1; ++i) {
             unsigned int index = i + j * wwi.width;
 
             if (wwi.constraint[index]) {
                 Pair window_pos = wwi.origin[index];
                 Pair current_pos = wwi.position[index];
                 Pair move = {window_pos.x - current_pos.x, window_pos.y - current_pos.y};
                 Pair accel = {move.x*m_stiffness, move.y*m_stiffness};
                 wwi.acceleration[index] = accel;
             } else {
                 Pair& pos = wwi.position[index];
                 neibourgs[0] = wwi.position[index-1];
                 neibourgs[1] = wwi.position[index+1];
                 neibourgs[2] = wwi.position[index-wwi.width];
                 neibourgs[3] = wwi.position[index+wwi.width];
 
                 acceleration.x = ((neibourgs[0].x - pos.x) - x_length) * m_stiffness +
                                  (x_length - (pos.x - neibourgs[1].x)) * m_stiffness +
                                  (neibourgs[2].x - pos.x) * m_stiffness +
                                  (neibourgs[3].x - pos.x) * m_stiffness;
                 acceleration.y = (y_length - (pos.y - neibourgs[2].y)) * m_stiffness +
                                  ((neibourgs[3].y - pos.y) - y_length) * m_stiffness +
                                  (neibourgs[0].y - pos.y) * m_stiffness +
                                  (neibourgs[1].y - pos.y) * m_stiffness;
 
                 acceleration.x /= 4;
                 acceleration.y /= 4;
 
                 wwi.acceleration[index] = acceleration;
             }
         }
     }
 
     heightRingLinearMean(&wwi.acceleration, wwi);
 
 #if defined COMPUTE_STATS
     Pair accBound = {m_maxAcceleration, m_minAcceleration};
     Pair velBound = {m_maxVelocity, m_minVelocity};
 #endif
 
     // compute the new velocity of each vertex.
     for (unsigned int i = 0; i < wwi.count; ++i) {
         Pair acc = wwi.acceleration[i];
         fixVectorBounds(acc, m_minAcceleration, m_maxAcceleration);
 
 #if defined COMPUTE_STATS
         computeVectorBounds(acc, accBound);
 #endif
 
         Pair& vel = wwi.velocity[i];
         vel.x = acc.x * time + vel.x * m_drag;
         vel.y = acc.y * time + vel.y * m_drag;
 
         acc_sum += fabs(acc.x) + fabs(acc.y);
     }
 
     heightRingLinearMean(&wwi.velocity, wwi);
 
     // compute the new pos of each vertex.
     for (unsigned int i = 0; i < wwi.count; ++i) {
         Pair& pos = wwi.position[i];
         Pair& vel = wwi.velocity[i];
 
         fixVectorBounds(vel, m_minVelocity, m_maxVelocity);
 #if defined COMPUTE_STATS
         computeVectorBounds(vel, velBound);
 #endif
 
         pos.x += vel.x * time * m_move_factor;
         pos.y += vel.y * time * m_move_factor;
 
         vel_sum += fabs(vel.x) + fabs(vel.y);
 
 #if defined VERBOSE_MODE
         if (wwi.constraint[i]) {
             qCDebug(KWINEFFECTS) << "Constraint point ** vel : " << vel.x << "," << vel.y << " ** move : " << vel.x*time << "," << vel.y*time;
         }
 #endif
     }
 
     if (!wwi.can_wobble_top) {
         for (unsigned int i = 0; i < wwi.width; ++i)
             for (unsigned j = 0; j < wwi.width - 1; ++j)
                 wwi.position[i+wwi.width*j].y = wwi.origin[i+wwi.width*j].y;
     }
     if (!wwi.can_wobble_bottom) {
         for (unsigned int i = wwi.width * (wwi.height - 1); i < wwi.count; ++i)
             for (unsigned j = 0; j < wwi.width - 1; ++j)
                 wwi.position[i-wwi.width*j].y = wwi.origin[i-wwi.width*j].y;
     }
     if (!wwi.can_wobble_left) {
         for (unsigned int i = 0; i < wwi.count; i += wwi.width)
             for (unsigned j = 0; j < wwi.width - 1; ++j)
                 wwi.position[i+j].x = wwi.origin[i+j].x;
     }
     if (!wwi.can_wobble_right) {
         for (unsigned int i = wwi.width - 1; i < wwi.count; i += wwi.width)
             for (unsigned j = 0; j < wwi.width - 1; ++j)
                 wwi.position[i-j].x = wwi.origin[i-j].x;
     }
 
 #if defined VERBOSE_MODE
 #   if defined COMPUTE_STATS
     qCDebug(KWINEFFECTS) << "Acceleration bounds (" << accBound.x << ", " << accBound.y << ")";
     qCDebug(KWINEFFECTS) << "Velocity bounds (" << velBound.x << ", " << velBound.y << ")";
 #   endif
     qCDebug(KWINEFFECTS) << "sum_acc : " << acc_sum << "  ***  sum_vel :" << vel_sum;
 #endif
 
     if (wwi.status != Moving && acc_sum < m_stopAcceleration && vel_sum < m_stopVelocity) {
         freeWobblyInfo(wwi);
         windows.remove(w);
         if (windows.isEmpty())
             effects->addRepaintFull();
         return false;
     }
 
     return true;
 }
 
 void WobblyWindowsEffect::heightRingLinearMean(Pair** data_pointer, WindowWobblyInfos& wwi)
 {
     Pair* data = *data_pointer;
     Pair neibourgs[8];
 
     // for corners
 
     // top-left
     {
         Pair& res = wwi.buffer[0];
         Pair vit = data[0];
         neibourgs[0] = data[1];
         neibourgs[1] = data[wwi.width];
         neibourgs[2] = data[wwi.width+1];
 
         res.x = (neibourgs[0].x + neibourgs[1].x + neibourgs[2].x + 3.0 * vit.x) / 6.0;
         res.y = (neibourgs[0].y + neibourgs[1].y + neibourgs[2].y + 3.0 * vit.y) / 6.0;
     }
 
 
     // top-right
     {
         Pair& res = wwi.buffer[wwi.width-1];
         Pair vit = data[wwi.width-1];
         neibourgs[0] = data[wwi.width-2];
         neibourgs[1] = data[2*wwi.width-1];
         neibourgs[2] = data[2*wwi.width-2];
 
         res.x = (neibourgs[0].x + neibourgs[1].x + neibourgs[2].x + 3.0 * vit.x) / 6.0;
         res.y = (neibourgs[0].y + neibourgs[1].y + neibourgs[2].y + 3.0 * vit.y) / 6.0;
     }
 
 
     // bottom-left
     {
         Pair& res = wwi.buffer[wwi.width*(wwi.height-1)];
         Pair vit = data[wwi.width*(wwi.height-1)];
         neibourgs[0] = data[wwi.width*(wwi.height-1)+1];
         neibourgs[1] = data[wwi.width*(wwi.height-2)];
         neibourgs[2] = data[wwi.width*(wwi.height-2)+1];
 
         res.x = (neibourgs[0].x + neibourgs[1].x + neibourgs[2].x + 3.0 * vit.x) / 6.0;
         res.y = (neibourgs[0].y + neibourgs[1].y + neibourgs[2].y + 3.0 * vit.y) / 6.0;
     }
 
 
     // bottom-right
     {
         Pair& res = wwi.buffer[wwi.count-1];
         Pair vit = data[wwi.count-1];
         neibourgs[0] = data[wwi.count-2];
         neibourgs[1] = data[wwi.width*(wwi.height-1)-1];
         neibourgs[2] = data[wwi.width*(wwi.height-1)-2];
 
         res.x = (neibourgs[0].x + neibourgs[1].x + neibourgs[2].x + 3.0 * vit.x) / 6.0;
         res.y = (neibourgs[0].y + neibourgs[1].y + neibourgs[2].y + 3.0 * vit.y) / 6.0;
     }
 
 
     // for borders
 
     // top border
     for (unsigned int i = 1; i < wwi.width - 1; ++i) {
         Pair& res = wwi.buffer[i];
         Pair vit = data[i];
         neibourgs[0] = data[i-1];
         neibourgs[1] = data[i+1];
         neibourgs[2] = data[i+wwi.width];
         neibourgs[3] = data[i+wwi.width-1];
         neibourgs[4] = data[i+wwi.width+1];
 
         res.x = (neibourgs[0].x + neibourgs[1].x + neibourgs[2].x + neibourgs[3].x + neibourgs[4].x + 5.0 * vit.x) / 10.0;
         res.y = (neibourgs[0].y + neibourgs[1].y + neibourgs[2].y + neibourgs[3].y + neibourgs[4].y + 5.0 * vit.y) / 10.0;
     }
 
     // bottom border
     for (unsigned int i = wwi.width * (wwi.height - 1) + 1; i < wwi.count - 1; ++i) {
         Pair& res = wwi.buffer[i];
         Pair vit = data[i];
         neibourgs[0] = data[i-1];
         neibourgs[1] = data[i+1];
         neibourgs[2] = data[i-wwi.width];
         neibourgs[3] = data[i-wwi.width-1];
         neibourgs[4] = data[i-wwi.width+1];
 
         res.x = (neibourgs[0].x + neibourgs[1].x + neibourgs[2].x + neibourgs[3].x + neibourgs[4].x + 5.0 * vit.x) / 10.0;
         res.y = (neibourgs[0].y + neibourgs[1].y + neibourgs[2].y + neibourgs[3].y + neibourgs[4].y + 5.0 * vit.y) / 10.0;
     }
 
     // left border
     for (unsigned int i = wwi.width; i < wwi.width*(wwi.height - 1); i += wwi.width) {
         Pair& res = wwi.buffer[i];
         Pair vit = data[i];
         neibourgs[0] = data[i+1];
         neibourgs[1] = data[i-wwi.width];
         neibourgs[2] = data[i+wwi.width];
         neibourgs[3] = data[i-wwi.width+1];
         neibourgs[4] = data[i+wwi.width+1];
 
         res.x = (neibourgs[0].x + neibourgs[1].x + neibourgs[2].x + neibourgs[3].x + neibourgs[4].x + 5.0 * vit.x) / 10.0;
         res.y = (neibourgs[0].y + neibourgs[1].y + neibourgs[2].y + neibourgs[3].y + neibourgs[4].y + 5.0 * vit.y) / 10.0;
     }
 
     // right border
     for (unsigned int i = 2 * wwi.width - 1; i < wwi.count - 1; i += wwi.width) {
         Pair& res = wwi.buffer[i];
         Pair vit = data[i];
         neibourgs[0] = data[i-1];
         neibourgs[1] = data[i-wwi.width];
         neibourgs[2] = data[i+wwi.width];
         neibourgs[3] = data[i-wwi.width-1];
         neibourgs[4] = data[i+wwi.width-1];
 
         res.x = (neibourgs[0].x + neibourgs[1].x + neibourgs[2].x + neibourgs[3].x + neibourgs[4].x + 5.0 * vit.x) / 10.0;
         res.y = (neibourgs[0].y + neibourgs[1].y + neibourgs[2].y + neibourgs[3].y + neibourgs[4].y + 5.0 * vit.y) / 10.0;
     }
 
     // for the inner points
     for (unsigned int j = 1; j < wwi.height - 1; ++j) {
         for (unsigned int i = 1; i < wwi.width - 1; ++i) {
             unsigned int index = i + j * wwi.width;
 
             Pair& res = wwi.buffer[index];
             Pair& vit = data[index];
             neibourgs[0] = data[index-1];
             neibourgs[1] = data[index+1];
             neibourgs[2] = data[index-wwi.width];
             neibourgs[3] = data[index+wwi.width];
             neibourgs[4] = data[index-wwi.width-1];
             neibourgs[5] = data[index-wwi.width+1];
             neibourgs[6] = data[index+wwi.width-1];
             neibourgs[7] = data[index+wwi.width+1];
 
             res.x = (neibourgs[0].x + neibourgs[1].x + neibourgs[2].x + neibourgs[3].x + neibourgs[4].x + neibourgs[5].x + neibourgs[6].x + neibourgs[7].x + 8.0 * vit.x) / 16.0;
             res.y = (neibourgs[0].y + neibourgs[1].y + neibourgs[2].y + neibourgs[3].y + neibourgs[4].y + neibourgs[5].y + neibourgs[6].y + neibourgs[7].y + 8.0 * vit.y) / 16.0;
         }
     }
 
     Pair* tmp = data;
     *data_pointer = wwi.buffer;
     wwi.buffer = tmp;
 }
 
 bool WobblyWindowsEffect::isActive() const
 {
     return !windows.isEmpty();
 }
 
 } // namespace KWin