diff --git a/containments/desktop/package/contents/ui/CompactRepresentation.qml b/containments/desktop/package/contents/ui/CompactRepresentation.qml
--- a/containments/desktop/package/contents/ui/CompactRepresentation.qml
+++ b/containments/desktop/package/contents/ui/CompactRepresentation.qml
@@ -24,6 +24,17 @@
 import org.kde.draganddrop 2.0 as DragDrop
 
 DragDrop.DropArea {
+    readonly property bool inPanel: (plasmoid.location == PlasmaCore.Types.TopEdge
+        || plasmoid.location == PlasmaCore.Types.RightEdge
+        || plasmoid.location == PlasmaCore.Types.BottomEdge
+        || plasmoid.location == PlasmaCore.Types.LeftEdge)
+
+    Layout.minimumWidth: plasmoid.formFactor === PlasmaCore.Types.Horizontal ? height : units.iconSizes.small
+    Layout.minimumHeight: plasmoid.formFactor === PlasmaCore.Types.Vertical ? width : (units.iconSizes.small + 2 * theme.mSize(theme.defaultFont).height)
+
+    Layout.maximumWidth: inPanel && plasmoid.formFactor != PlasmaCore.Types.Vertical ? units.iconSizeHints.panel : -1
+    Layout.maximumHeight: inPanel && plasmoid.formFactor != PlasmaCore.Types.Vertical ? units.iconSizeHints.panel : -1
+
     property Item folderView: null
 
     onContainsDragChanged: {
diff --git a/containments/desktop/package/contents/ui/main.qml b/containments/desktop/package/contents/ui/main.qml
--- a/containments/desktop/package/contents/ui/main.qml
+++ b/containments/desktop/package/contents/ui/main.qml
@@ -37,15 +37,35 @@
     id: root
     objectName: isFolder ? "folder" : "desktop"
 
-    width: isPopup ? undefined : preferredWidth(false) // for the initial size when placed on the desktop
-    Layout.minimumWidth: preferredWidth(true)
-    Layout.preferredWidth: isPopup ? preferredWidth(false) : 0 // for the popup size to change at runtime when view mode changes
-    Plasmoid.switchWidth: isPopup ? units.iconSizeHints.panel : preferredWidth(true)
-
+    width: isPopup ? undefined : preferredWidth(false)
     height: isPopup ? undefined : preferredHeight(false)
-    Layout.minimumHeight: preferredHeight(true)
-    Layout.preferredHeight: isPopup ? preferredHeight(false) : 0
-    Plasmoid.switchHeight: isPopup ? units.iconSizeHints.panel : preferredHeight(true)
+
+    Layout.minimumWidth: preferredWidth(!isPopup)
+    Layout.minimumHeight: preferredHeight(!isPopup)
+
+    Layout.preferredWidth: preferredWidth(false)
+    Layout.preferredHeight: preferredHeight(false)
+
+    Layout.maximumWidth: isPopup ? preferredWidth(false) : -1
+    Layout.maximumHeight: isPopup ? preferredHeight(false) : -1
+
+    Plasmoid.switchWidth: {
+        // Support expanding into the full representation only on vertical panels.
+        if (isPopup && plasmoid.formFactor == PlasmaCore.Types.Vertical) {
+            return units.iconSizeHints.panel;
+        }
+
+        return undefined;
+    }
+
+    Plasmoid.switchHeight: {
+        // Support expanding into the full representation only on vertical panels.
+        if (isPopup && plasmoid.formFactor == PlasmaCore.Types.Vertical) {
+            return units.iconSizeHints.panel;
+        }
+
+        return undefined;
+    }
 
     LayoutMirroring.enabled: Qt.application.layoutDirection === Qt.RightToLeft
     LayoutMirroring.childrenInherit: true