diff --git a/lib/kcommondecoration.cpp b/lib/kcommondecoration.cpp
index 56b8e8ff00..d9f3661284 100644
--- a/lib/kcommondecoration.cpp
+++ b/lib/kcommondecoration.cpp
@@ -744,10 +744,6 @@ ButtonType KCommonDecorationButton::type()
     return m_type;;
 }
 
-void KCommonDecorationButton::reset(unsigned long)
-{
-}
-
 void KCommonDecorationButton::setRealizeButtons(int btns)
 {
     m_realizeButtons = btns;
@@ -755,7 +751,7 @@ void KCommonDecorationButton::setRealizeButtons(int btns)
 
 void KCommonDecorationButton::setSize(const QSize &s)
 {
-    if (s != size() ) {
+    if (!m_size.isValid() || s != size() ) {
         m_size = s;
 
         setFixedSize(m_size);
diff --git a/lib/kcommondecoration.h b/lib/kcommondecoration.h
index 2f8a71898c..dd6b25cef0 100644
--- a/lib/kcommondecoration.h
+++ b/lib/kcommondecoration.h
@@ -278,7 +278,7 @@ class KWIN_EXPORT KCommonDecorationButton : public QButton
 
     public:
         KCommonDecorationButton(ButtonType type, KCommonDecoration *parent, const char *name);
-        ~KCommonDecorationButton();
+        virtual ~KCommonDecorationButton();
 
         /**
          * These flags specify what has changed, e.g. the reason for a reset().
@@ -294,7 +294,7 @@ class KWIN_EXPORT KCommonDecorationButton : public QButton
         /**
          * Initialize the button after size change etc.
          */
-        virtual void reset(unsigned long changed);
+        virtual void reset(unsigned long changed) = 0;
         /**
          * @returns the KCommonDecoration the button belongs to.
          */