diff --git a/src/private/multisplitter/Item.cpp b/src/private/multisplitter/Item.cpp
index 4d3e92b7..abd90022 100644
--- a/src/private/multisplitter/Item.cpp
+++ b/src/private/multisplitter/Item.cpp
@@ -413,8 +413,8 @@ void Item::setIsVisible(bool is)
         Q_EMIT visibleChanged(this, is);
 
         if (auto w = frame()) {
-            w->setGeometry(mapToRoot(m_sizingInfo.geometry));
-            w->setVisible(is);
+            w->setGeometry(mapToRoot(m_sizingInfo.geometry)); // TODO
+            w->setVisible(is); // TODO: Only set visible when apply*() ?
         }
     }
 }
@@ -849,7 +849,7 @@ ItemContainer *ItemContainer::convertChildToContainer(Item *leaf)
 
 void ItemContainer::insertItem(Item *item, Location loc, AddingOption option)
 {
-    item->setIsVisible(false);
+    item->setIsVisible(false); // TODO: why ?
 
     Q_ASSERT(item != this);
     if (contains(item)) {
@@ -1501,11 +1501,8 @@ void ItemContainer::resize(QSize newSize) // Rename to setSize_recursive
     for (int i = 0; i < count; ++i) {
         SizingInfo &size = childSizes[i];
         const int missing = size.missingLength(m_orientation);
-        if (missing == 0)
-            continue;
-
-        growItem(i, childSizes, missing, GrowthStrategy::BothSidesEqually);
-        size.setLength(size.minLength(m_orientation), m_orientation); // TODO: growItem should do it instead ?
+        if (missing > 0)
+            growItem(i, childSizes, missing, GrowthStrategy::BothSidesEqually);
     }
 
     // #3 Sizes are now correct and honour min/max sizes. So apply them to our Items
@@ -1596,15 +1593,22 @@ void ItemContainer::restoreChild(Item *item)
 
     const int available = availableOnSide(item, Side1) + availableOnSide(item, Side2) - Item::separatorThickness();
 
+    const QSize proposedSize = item->size();
     const int max = available;
     const int min = item->minLength(m_orientation);
-    const int proposed = item->length(m_orientation);
+    const int proposed = Layouting::length(proposedSize, m_orientation);
     const int newLength = qBound(min, proposed, max);
 
-    item->setLength_recursive(newLength, m_orientation);
     Q_ASSERT(item->isVisible());
-    growItem(item, newLength, GrowthStrategy::BothSidesEqually, /*accountForNewSeparator=*/ true);
 
+    // growItem() will make it grow by the same amount it steals from the neighbours, so we can't start the growing without zeroing it
+    if (isVertical()) {
+        item->m_sizingInfo.geometry.setHeight(0);
+    } else {
+        item->m_sizingInfo.geometry.setWidth(0);
+    }
+
+    growItem(item, newLength, GrowthStrategy::BothSidesEqually, /*accountForNewSeparator=*/ true);
     updateChildPercentages();
 }
 
@@ -1614,6 +1618,12 @@ void ItemContainer::updateWidgetGeometries()
         item->updateWidgetGeometries();
 }
 
+int ItemContainer::oppositeLength() const
+{
+    return isVertical() ? width()
+                        : height();
+}
+
 Item *ItemContainer::visibleNeighbourFor(const Item *item, Side side) const
 {
     // Item might not be visible, so use m_children instead of visibleChildren()
@@ -1871,7 +1881,8 @@ void ItemContainer::growNeighbours(Item *side1Neighbour, Item *side2Neighbour)
     }
 }
 
-void ItemContainer::growItem(int index, SizingInfo::List &sizes, int missing, GrowthStrategy growthStrategy, bool accountForNewSeparator)
+void ItemContainer::growItem(int index, SizingInfo::List &sizes, int missing,
+                             GrowthStrategy, bool accountForNewSeparator)
 {
     int toSteal = missing; // The amount that neighbours of @p index will shrink
     if (accountForNewSeparator)
@@ -1881,16 +1892,19 @@ void ItemContainer::growItem(int index, SizingInfo::List &sizes, int missing, Gr
     if (toSteal == 0)
         return;
 
+    // #1. Grow our item
     SizingInfo &sizingInfo = sizes[index];
+    sizingInfo.setLength(sizingInfo.length(m_orientation) + missing, m_orientation);
+    sizingInfo.setOppositeLength(oppositeLength(), m_orientation);
 
-    Q_ASSERT(growthStrategy == GrowthStrategy::BothSidesEqually);
     const int count = sizes.count();
     if (count == 1) {
         //There's no neighbours to push, we're alone. Occupy the full container
-        sizingInfo.setLength(sizingInfo.length(m_orientation) + missing, m_orientation);
+        sizingInfo.incrementLength(missing, m_orientation);
         return;
     }
 
+    // #2. Now shrink the neigbours by the same amount. Calculate how much to shrink from each side
     const LengthOnSide side1Length = lengthOnSide(sizes, index - 1, Side1, m_orientation);
     const LengthOnSide side2Length = lengthOnSide(sizes, index + 1, Side2, m_orientation);
 
diff --git a/src/private/multisplitter/Item_p.h b/src/private/multisplitter/Item_p.h
index 0e683bf0..52aeb8cd 100644
--- a/src/private/multisplitter/Item_p.h
+++ b/src/private/multisplitter/Item_p.h
@@ -215,6 +215,14 @@ struct SizingInfo {
         }
     }
 
+    void incrementLength(int byAmount, Qt::Orientation o) {
+        setLength(length(o) + byAmount, o);
+    }
+
+    void setOppositeLength(int l, Qt::Orientation o) {
+        setLength(l, oppositeOrientation(o));
+    }
+
     void setPos(int p, Qt::Orientation o) {
         if (o == Qt::Vertical)
             geometry.moveTop(p);
@@ -234,7 +242,6 @@ struct SizingInfo {
     QRect geometry;
     QSize minSize = QSize(40, 40); // TODO: Hardcoded
     QSize maxSize = QSize(16777215, 16777215); // TODO: Not supported yet
-    QSize proposedSize;
     double percentageWithinParent = 0.0;
     bool isBeingInserted = false;
 };
@@ -426,6 +433,7 @@ public:
     void updateChildPercentages();
     void restoreChild(Item *);
     void updateWidgetGeometries() override;
+    int oppositeLength() const;
 
     ///@brief Grows the side1Neighbour to the right and the side2Neighbour to the left
     ///So they occupy the empty space that's between them (or bottom/top if Qt::Vertical).