Fixes for various invalid type conversions

Include/Rocket/Core/Decorator.h

@@ -85,6 +85,9 @@ public:
 	/// @param[in] element_data The handle to the data generated by the decorator for the element.
 	virtual void RenderElement(Element* element, DecoratorDataHandle element_data) = 0;
 
+	/// Value specifying an invalid or non-existent Decorator data handle.
+	static const DecoratorDataHandle INVALID_DECORATORDATAHANDLE = 0;
+
 protected:
 	/// Releases the decorator through its instancer.
 	virtual void OnReferenceDeactivate();

Samples/invaders/src/DecoratorDefender.cpp

@@ -49,7 +49,7 @@ bool DecoratorDefender::Initialise(const Rocket::Core::String& image_source, con
 /// Called on a decorator to generate any required per-element data for a newly decorated element.
 Rocket::Core::DecoratorDataHandle DecoratorDefender::GenerateElementData(Rocket::Core::Element* ROCKET_UNUSED(element))
 {
-	return NULL;
+	return Rocket::Core::Decorator::INVALID_DECORATORDATAHANDLE;
 }
 
 // Called to release element data generated by this decorator.

Samples/pyinvaders/src/DecoratorDefender.cpp

@@ -49,7 +49,7 @@ bool DecoratorDefender::Initialise(const Rocket::Core::String& image_source, con
 /// Called on a decorator to generate any required per-element data for a newly decorated element.
 Rocket::Core::DecoratorDataHandle DecoratorDefender::GenerateElementData(Rocket::Core::Element* ROCKET_UNUSED(element))
 {
-	return NULL;
+	return Rocket::Core::Decorator::INVALID_DECORATORDATAHANDLE;
 }
 
 // Called to release element data generated by this decorator.

Samples/pyinvaders/src/DecoratorStarfield.cpp

@@ -85,7 +85,7 @@ Rocket::Core::DecoratorDataHandle DecoratorStarfield::GenerateElementData(Rocket
 		star_field->last_update = Shell::GetElapsedTime();
 	}
 
-	return star_field;
+	return reinterpret_cast<Rocket::Core::DecoratorDataHandle>(star_field);
 }
 
 // Called to release element data generated by this decorator.

Samples/tutorial/datagrid/src/DecoratorDefender.cpp

@@ -33,7 +33,7 @@ bool DecoratorDefender::Initialise(const Rocket::Core::String& image_source, con
 /// Called on a decorator to generate any required per-element data for a newly decorated element.
 Rocket::Core::DecoratorDataHandle DecoratorDefender::GenerateElementData(Rocket::Core::Element* ROCKET_UNUSED(element))
 {
-	return NULL;
+	return Rocket::Core::Decorator::INVALID_DECORATORDATAHANDLE;
 }
 
 // Called to release element data generated by this decorator.

Samples/tutorial/datagrid_tree/src/DecoratorDefender.cpp

@@ -33,7 +33,7 @@ bool DecoratorDefender::Initialise(const Rocket::Core::String& image_source, con
 /// Called on a decorator to generate any required per-element data for a newly decorated element.
 Rocket::Core::DecoratorDataHandle DecoratorDefender::GenerateElementData(Rocket::Core::Element* ROCKET_UNUSED(element))
 {
-	return NULL;
+	return Rocket::Core::Decorator::INVALID_DECORATORDATAHANDLE;
 }
 
 // Called to release element data generated by this decorator.