diff --git a/planet/Objects.ocd/Libraries.ocd/Mechanisms.ocd/SwitchTarget.ocd/Script.c b/planet/Objects.ocd/Libraries.ocd/Mechanisms.ocd/SwitchTarget.ocd/Script.c
index 6c8d9bedc..bae3149af 100755
--- a/planet/Objects.ocd/Libraries.ocd/Mechanisms.ocd/SwitchTarget.ocd/Script.c
+++ b/planet/Objects.ocd/Libraries.ocd/Mechanisms.ocd/SwitchTarget.ocd/Script.c
@@ -21,7 +21,6 @@ public func Construction(object by_object)
 {
 	_inherited(by_object, ...);
 	lib_mechanism = {
-		old_signal = nil,		// the last received signal
 		set_plr_view = true,	// sets the player view to this object when the input signal changes
 		temp_light = nil,		// temporary light, so that the player can see something when the object is being operated
 	};
@@ -32,47 +31,36 @@ public func Construction(object by_object)
 /*
  Sets the input signal of this mechanism.
  
- The function issues two callbacks to the object:
- a) OnInputSignalChanged(operator, sender, value) => gets called only if the value changes
- b) OnInputSignalSet(operator, sender, value) => gets called every time the signal is set
+ This function should handle everything that happens when the input
+ signal is set (on the generic level).
+ For the object-specific functionality this function issues a callback to the object:
+ * OnSetInputSignal(operator, sender, value)
  
- Use these callbacks to activate or deactivate certain functions in the mechanism.
+ Use the callback to activate or deactivate certain functions in the mechanism.
  For example, the stone door opens if you pass 'true', and closes if you pass 'false'
-
- Usually only the signal changed callback should be relevant, but who knows. Callback b)
- can be removed at any time if it turns out to be unnecessary.
+ 
+ That callback happens after the generic handling is done, so that the object
+ can safely be deleted in the callback.
 
  @par operator this object is operating the mechanism or the object that sent the signal-
  @par sender this object sent the signal - this is usually a switch.
  @par value this value is sent.
 */
-public func SetInputSignal(object operator, object sender, bool new_signal)
+public func SetInputSignal(object operator, object sender, bool value)
 {
-	var self = this;
-
-	// Callback type 1: rising/falling edge
-	if (lib_mechanism.old_signal != new_signal)
+	// Show the object being operated
+	if (operator && lib_mechanism.set_plr_view)
 	{
-		this->~OnInputSignalChanged(operator, sender, new_signal);
-		lib_mechanism.old_signal = new_signal;
-		
-		// Show the object being operated
-		if (self && operator && lib_mechanism.set_plr_view)
+		SetPlrView(operator->GetController(), this);
+		if (lib_mechanism.temp_light)
 		{
-			SetPlrView(operator->GetController(), this);
-			if (lib_mechanism.temp_light)
-			{
-				lib_mechanism.temp_light->RemoveObject();
-			}
-			lib_mechanism.temp_light = Global->CreateLight(this->GetX(), this->GetY() + this->~GetFloorOffset(), 30, Fx_Light.LGT_Temp, operator->GetController(), 30, 50);
+			lib_mechanism.temp_light->RemoveObject();
 		}
+		lib_mechanism.temp_light = Global->CreateLight(this->GetX(), this->GetY() + this->~GetFloorOffset(), 30, Fx_Light.LGT_Temp, operator->GetController(), 30, 50);
 	}
 
-	// Callback type 2: current signal
-	if (self)
-	{
-		this->~OnInputSignalSet(operator, sender, new_signal);
-	}
+	// Callback: current signal
+	this->~OnSetInputSignal(operator, sender, value);
 }
 
 
diff --git a/planet/Objects.ocd/Structures.ocd/StoneDoor.ocd/Script.c b/planet/Objects.ocd/Structures.ocd/StoneDoor.ocd/Script.c
index ad54724a5..9578b03e1 100644
--- a/planet/Objects.ocd/Structures.ocd/StoneDoor.ocd/Script.c
+++ b/planet/Objects.ocd/Structures.ocd/StoneDoor.ocd/Script.c
@@ -63,7 +63,7 @@ private func ForceDigFree()
 /*-- Switch control --*/
 
 // Reaction to operation by a switch: if open_door is true the door opens, otherwise it closes
-public func OnInputSignalChanged(object operator, object switch, bool open_door)
+public func OnSetInputSignal(object operator, object switch, bool open_door)
 {
 	if (open_door)
 	{