diff --git a/planet/Objects.c4d/Clonk.c4d/Script.c b/planet/Objects.c4d/Clonk.c4d/Script.c
index c782cd655..1b0f5d935 100644
--- a/planet/Objects.c4d/Clonk.c4d/Script.c
+++ b/planet/Objects.c4d/Clonk.c4d/Script.c
@@ -5,9 +5,6 @@
 	The protoganist of the game. Witty and nimble if skillfully controled ;-)
 	
 	TODO:
-	+ You should write a lot about the functioning of the animations-system,
-	holding weapons etc. and/or put that into a separate library - Newton
-	
 	+ replace German comments
 */
 
@@ -47,7 +44,6 @@ protected func Construction()
 
 	AddEffect("IntTurn", this, 1, 1, this);
 	AddEffect("IntEyes", this, 1, 35+Random(4), this);
-	AddEffect("Bubble", this, 1, 72, this);
 }
 
 
@@ -1716,9 +1712,24 @@ func FxIntRidingStop(pTarget, iNumber, fTmp)
 		pMount->~OnUnmount(this);
 }
 
+// calback from engine
+func OnMaterialChanged(int new, int old)
+{
+	var newdens = GetMaterialVal("Density","Material",new);
+	var olddens = GetMaterialVal("Density","Material",old);
+	var newliquid = (newdens >= C4M_Liquid) && (newdens < C4M_Solid);
+	var oldliquid = (olddens >= C4M_Liquid) && (olddens < C4M_Solid);
+	// into water
+	if(newliquid && !oldliquid)
+		AddEffect("Bubble", this, 1, 72, this);
+	// out of water
+	else if(!newliquid && oldliquid)
+		RemoveEffect("Bubble", this);
+}
+
 func FxBubbleTimer(pTarget, iNumber, iTime)
 {
-	if(GBackLiquid(0,-4)) Bubble();
+	Bubble();
 }
 
 func StartPushing()
diff --git a/src/game/object/C4Object.cpp b/src/game/object/C4Object.cpp
index b1892a5b7..2f1cf04c6 100644
--- a/src/game/object/C4Object.cpp
+++ b/src/game/object/C4Object.cpp
@@ -729,6 +729,23 @@ void C4Object::ComponentConGain()
 		                   Max<int32_t>(Component.GetCount(cnt),Def->Component.GetCount(cnt)*Con/FullCon));
 }
 
+void C4Object::UpdateInMat()
+{
+	// get new mat
+	int32_t newmat;
+	if (Contained)
+		newmat = Contained->Def->ClosedContainer ? MNone : Contained->InMat;
+	else
+		newmat = GBackMat(GetX(), GetY());
+
+	// mat changed?
+	if (newmat != InMat)
+	{
+		Call(PSF_OnMaterialChanged,&C4AulParSet(C4VInt(newmat),C4VInt(InMat)));
+		InMat = newmat;
+	}
+}
+
 void C4Object::SetOCF()
 {
 	C4PropList* pActionDef = GetAction();
@@ -743,10 +760,7 @@ void C4Object::SetOCF()
 	else if (Contained && !Contained->Status)
 		{ LogF("Warning: contained in deleted object %p (%s)!", static_cast<void*>(Contained), Contained->GetName()); }
 #endif
-	if (Contained)
-		InMat = Contained->Def->ClosedContainer ? MNone : Contained->InMat;
-	else
-		InMat = GBackMat(GetX(), GetY());
+	UpdateInMat();
 	// OCF_Normal: The OCF is never zero
 	OCF=OCF_Normal;
 	// OCF_Construct: Can be built outside
@@ -882,10 +896,7 @@ void C4Object::UpdateOCF()
 	else if (Contained && !Contained->Status)
 		{ LogF("Warning: contained in deleted object %p (%s)!", static_cast<void*>(Contained), Contained->GetName()); }
 #endif
-	if (Contained)
-		InMat = Contained->Def->ClosedContainer ? MNone : Contained->InMat;
-	else
-		InMat = GBackMat(GetX(), GetY());
+	UpdateInMat();
 	// Keep the bits that only have to be updated with SetOCF (def, category, con, alive, onfire)
 	OCF=OCF & (OCF_Normal | OCF_Exclusive | OCF_Edible | OCF_Grab | OCF_FullCon
 	           /*| OCF_Chop - now updated regularly, see below */
diff --git a/src/game/object/C4Object.h b/src/game/object/C4Object.h
index 530b81daa..7c0e08ea2 100644
--- a/src/game/object/C4Object.h
+++ b/src/game/object/C4Object.h
@@ -131,6 +131,8 @@ public:
 
 class C4Object: public C4PropListNumbered
 {
+private:
+	void UpdateInMat();
 public:
 	C4Object();
 	~C4Object();
diff --git a/src/game/script/C4Script.h b/src/game/script/C4Script.h
index a48ccb216..e2f1540c6 100644
--- a/src/game/script/C4Script.h
+++ b/src/game/script/C4Script.h
@@ -190,6 +190,7 @@ bool C4ValueToMatrix(const C4ValueArray& array, StdMeshMatrix* matrix);
 #define PSF_NameChange               "~OnNameChanged" // bool inInfoSection
 #define PSF_OnWealthChanged          "~OnWealthChanged" // int iPlr
 #define PSF_OnActionChanged          "~OnActionChanged" // string oldaction
+#define PSF_OnMaterialChanged        "~OnMaterialChanged" // int newmat, int oldmat
 
 // Fx%s is automatically prefixed
 #define PSFS_FxAdd              "Add" // C4Object *pTarget, int iEffectNumber, C4String *szNewEffect, int iNewTimer, C4Value vNewEffectVar1, C4Value vNewEffectVar2, C4Value vNewEffectVar3, C4Value vNewEffectVar4