diff --git a/placement.cpp b/placement.cpp
--- a/placement.cpp
+++ b/placement.cpp
@@ -500,8 +500,9 @@
 {
     const auto parent = c->transientFor();
     const QRect screen =  Workspace::self()->clientArea(parent->isFullScreen() ? FullScreenArea : PlacementArea, parent);
-    const QPoint popupPos = c->transientPlacement(screen).topLeft();
-    c->move(popupPos);
+    const QRect popupGeometry = c->transientPlacement(screen);
+    c->setGeometry(popupGeometry);
+
 
     // Potentially a client could set no constraint adjustments
     // and we'll be offscreen.
diff --git a/shell_client.h b/shell_client.h
--- a/shell_client.h
+++ b/shell_client.h
@@ -210,7 +210,7 @@
     void updateMaximizeMode(MaximizeMode maximizeMode);
     // called on surface commit and processes all m_pendingConfigureRequests up to m_lastAckedConfigureReqest
     void updatePendingGeometry();
-    QPoint popupOffset(const QRect &anchorRect, const Qt::Edges anchorEdge, const Qt::Edges gravity) const;
+    QPoint popupOffset(const QRect &anchorRect, const Qt::Edges anchorEdge, const Qt::Edges gravity, const QSize popupSize) const;
     static void deleteClient(ShellClient *c);
 
     KWayland::Server::ShellSurfaceInterface *m_shellSurface;
diff --git a/shell_client.cpp b/shell_client.cpp
--- a/shell_client.cpp
+++ b/shell_client.cpp
@@ -1453,6 +1453,7 @@
     Qt::Edges gravity;
     QPoint offset;
     PositionerConstraints constraintAdjustments;
+    QSize size = geometry().size();
 
     const QPoint parentClientPos = transientFor()->pos() + transientFor()->clientPos();
     QRect popupPosition;
@@ -1486,12 +1487,16 @@
         gravity = m_xdgShellPopup->gravity();
         offset = m_xdgShellPopup->anchorOffset();
         constraintAdjustments = m_xdgShellPopup->constraintAdjustments();
+        if (!size.isValid()) {
+            size = m_xdgShellPopup->initialSize();
+        }
     } else {
         Q_UNREACHABLE();
     }
 
+
     //initial position
-    popupPosition = QRect(popupOffset(anchorRect, anchorEdge, gravity) + offset + parentClientPos, geometry().size());
+    popupPosition = QRect(popupOffset(anchorRect, anchorEdge, gravity, size) + offset + parentClientPos, size);
 
     //if that fits, we don't need to do anything
     if (inBounds(popupPosition)) {
@@ -1510,20 +1515,21 @@
             if (flippedGravity & (Qt::LeftEdge | Qt::RightEdge)) {
                 flippedGravity ^= (Qt::LeftEdge | Qt::RightEdge);
             }
-            auto flippedPopupPosition = QRect(popupOffset(anchorRect, flippedAnchorEdge, flippedGravity) + offset + parentClientPos, geometry().size());
+            auto flippedPopupPosition = QRect(popupOffset(anchorRect, flippedAnchorEdge, flippedGravity, size) + offset + parentClientPos, size);
 
             //if it still doesn't fit we should continue with the unflipped version
             if (inBounds(flippedPopupPosition, Qt::LeftEdge | Qt::RightEdge)) {
-                popupPosition.setX(flippedPopupPosition.x());
+                popupPosition.moveLeft(flippedPopupPosition.x());
             }
         }
     }
     if (constraintAdjustments & PositionerConstraint::SlideX) {
         if (!inBounds(popupPosition, Qt::LeftEdge)) {
-            popupPosition.setX(bounds.x());
+            popupPosition.moveLeft(bounds.x());
         }
         if (!inBounds(popupPosition, Qt::RightEdge)) {
-            popupPosition.setX(bounds.x() + bounds.width() - geometry().width());
+            // moveRight suffers from the classic QRect off by one issue
+            popupPosition.moveLeft(bounds.x() + bounds.width() - size.width());
         }
     }
     if (constraintAdjustments & PositionerConstraint::ResizeX) {
@@ -1542,20 +1548,20 @@
             if (flippedGravity & (Qt::TopEdge | Qt::BottomEdge)) {
                 flippedGravity ^= (Qt::TopEdge | Qt::BottomEdge);
             }
-            auto flippedPopupPosition = QRect(popupOffset(anchorRect, flippedAnchorEdge, flippedGravity) + offset + parentClientPos, geometry().size());
+            auto flippedPopupPosition = QRect(popupOffset(anchorRect, flippedAnchorEdge, flippedGravity, size) + offset + parentClientPos, size);
 
             //if it still doesn't fit we should continue with the unflipped version
             if (inBounds(flippedPopupPosition, Qt::TopEdge | Qt::BottomEdge)) {
-                popupPosition.setY(flippedPopupPosition.y());
+                popupPosition.moveTop(flippedPopupPosition.y());
             }
         }
     }
     if (constraintAdjustments & PositionerConstraint::SlideY) {
         if (!inBounds(popupPosition, Qt::TopEdge)) {
-            popupPosition.setY(bounds.y());
+            popupPosition.moveTop(bounds.y());
         }
         if (!inBounds(popupPosition, Qt::BottomEdge)) {
-            popupPosition.setY(bounds.y() + bounds.height() - geometry().height());
+            popupPosition.moveTop(bounds.y() + bounds.height() - size.height());
         }
     }
     if (constraintAdjustments & PositionerConstraint::ResizeY) {
@@ -1565,9 +1571,8 @@
     return popupPosition;
 }
 
-QPoint ShellClient::popupOffset(const QRect &anchorRect, const Qt::Edges anchorEdge, const Qt::Edges gravity) const
+QPoint ShellClient::popupOffset(const QRect &anchorRect, const Qt::Edges anchorEdge, const Qt::Edges gravity, const QSize popupSize) const
 {
-    const QSize popupSize = geometry().size();
     QPoint anchorPoint;
     switch (anchorEdge & (Qt::LeftEdge | Qt::RightEdge)) {
     case Qt::LeftEdge: