diff --git a/source/blender/editors/interface/interface.c b/source/blender/editors/interface/interface.c
index 00b2d922ffc..b4b96f46173 100644
--- a/source/blender/editors/interface/interface.c
+++ b/source/blender/editors/interface/interface.c
@@ -2546,7 +2546,7 @@ static uiBut *ui_def_but_rna(uiBlock *block, int type, int retval, const char *s
 		}
 	}
 	else {
-		printf("ui_def_but_rna: property not found: %s.%s\n", RNA_struct_identifier(ptr->type), propname);
+		RNA_warning("ui_def_but_rna: property not found: %s.%s\n", RNA_struct_identifier(ptr->type), propname);
 		str= propname;
 	}
 
diff --git a/source/blender/editors/interface/interface_layout.c b/source/blender/editors/interface/interface_layout.c
index c94c3a7813a..a208eee1649 100644
--- a/source/blender/editors/interface/interface_layout.c
+++ b/source/blender/editors/interface/interface_layout.c
@@ -609,15 +609,16 @@ static void ui_item_disabled(uiLayout *layout, const char *name)
 }
 
 /* operator items */
-PointerRNA uiItemFullO(uiLayout *layout, const char *idname, const char *name, int icon, IDProperty *properties, int context, int flag)
+PointerRNA uiItemFullO(uiLayout *layout, const char *opname, const char *name, int icon, IDProperty *properties, int context, int flag)
 {
 	uiBlock *block= layout->root->block;
-	wmOperatorType *ot= WM_operatortype_find(idname, 0);
+	wmOperatorType *ot= WM_operatortype_find(opname, 1);
 	uiBut *but;
 	int w;
 
 	if(!ot) {
-		ui_item_disabled(layout, idname);
+		ui_item_disabled(layout, opname);
+		RNA_warning("uiItemFullO: unknown operator '%s'\n", opname);
 		return PointerRNA_NULL;
 	}
 
@@ -713,7 +714,7 @@ void uiItemEnumO(uiLayout *layout, const char *opname, const char *name, int ico
 
 void uiItemsFullEnumO(uiLayout *layout, const char *opname, const char *propname, IDProperty *properties, int context, int flag)
 {
-	wmOperatorType *ot= WM_operatortype_find(opname, 0);
+	wmOperatorType *ot= WM_operatortype_find(opname, 1);
 	PointerRNA ptr;
 	PropertyRNA *prop;
 	uiBut *bt;
@@ -721,6 +722,7 @@ void uiItemsFullEnumO(uiLayout *layout, const char *opname, const char *propname
 
 	if(!ot || !ot->srna) {
 		ui_item_disabled(layout, opname);
+		RNA_warning("uiItemsFullEnumO: %s '%s'\n", ot ? "unknown operator" : "operator missing srna", opname);
 		return;
 	}
 
@@ -795,7 +797,7 @@ void uiItemEnumO_value(uiLayout *layout, const char *name, int icon, const char
 		/* pass */
 	}
 	else {
-		printf("uiItemEnumO_value: %s.%s not found.\n", RNA_struct_identifier(ptr.type), propname);
+		RNA_warning("uiItemEnumO_value: %s.%s not found.\n", RNA_struct_identifier(ptr.type), propname);
 		return;
 	}
 
@@ -824,7 +826,7 @@ void uiItemEnumO_string(uiLayout *layout, const char *name, int icon, const char
 		RNA_property_enum_items(layout->root->block->evil_C, &ptr, prop, &item, NULL, &free);
 		if(item==NULL || RNA_enum_value_from_id(item, value_str, &value)==0) {
 			if(free) MEM_freeN(item);
-			printf("uiItemEnumO_string: %s.%s, enum %s not found.\n", RNA_struct_identifier(ptr.type), propname, value_str);
+			RNA_warning("uiItemEnumO_string: %s.%s, enum %s not found.\n", RNA_struct_identifier(ptr.type), propname, value_str);
 			return;
 		}
 
@@ -832,7 +834,7 @@ void uiItemEnumO_string(uiLayout *layout, const char *name, int icon, const char
 			MEM_freeN(item);
 	}
 	else {
-		printf("uiItemEnumO_string: %s.%s not found.\n", RNA_struct_identifier(ptr.type), propname);
+		RNA_warning("uiItemEnumO_string: %s.%s not found.\n", RNA_struct_identifier(ptr.type), propname);
 		return;
 	}
 	
@@ -1038,7 +1040,7 @@ void uiItemR(uiLayout *layout, PointerRNA *ptr, const char *propname, int flag,
 
 	if(!prop) {
 		ui_item_disabled(layout, propname);
-		printf("uiItemR: property not found: %s.%s\n", RNA_struct_identifier(ptr->type), propname);
+		RNA_warning("uiItemR: property not found: %s.%s\n", RNA_struct_identifier(ptr->type), propname);
 		return;
 	}
 
@@ -1051,7 +1053,7 @@ void uiItemEnumR(uiLayout *layout, const char *name, int icon, struct PointerRNA
 
 	if(!prop || RNA_property_type(prop) != PROP_ENUM) {
 		ui_item_disabled(layout, propname);
-		printf("uiItemEnumR: property not found: %s.%s\n", RNA_struct_identifier(ptr->type), propname);
+		RNA_warning("uiItemEnumR: property not found: %s.%s\n", RNA_struct_identifier(ptr->type), propname);
 		return;
 	}
 
@@ -1066,7 +1068,7 @@ void uiItemEnumR_string(uiLayout *layout, struct PointerRNA *ptr, const char *pr
 
 	if(!prop || RNA_property_type(prop) != PROP_ENUM) {
 		ui_item_disabled(layout, propname);
-		printf("uiItemEnumR_string: enum property not found: %s.%s\n", RNA_struct_identifier(ptr->type), propname);
+		RNA_warning("uiItemEnumR_string: enum property not found: %s.%s\n", RNA_struct_identifier(ptr->type), propname);
 		return;
 	}
 
@@ -1075,7 +1077,7 @@ void uiItemEnumR_string(uiLayout *layout, struct PointerRNA *ptr, const char *pr
 	if(!RNA_enum_value_from_id(item, value, &ivalue)) {
 		if(free) MEM_freeN(item);
 		ui_item_disabled(layout, propname);
-		printf("uiItemEnumR: enum property value not found: %s\n", value);
+		RNA_warning("uiItemEnumR: enum property value not found: %s\n", value);
 		return;
 	}
 
@@ -1100,10 +1102,15 @@ void uiItemsEnumR(uiLayout *layout, struct PointerRNA *ptr, const char *propname
 
 	if(!prop) {
 		ui_item_disabled(layout, propname);
+		RNA_warning("uiItemsEnumR: enum property not found: %s.%s\n", RNA_struct_identifier(ptr->type), propname);
 		return;
 	}
 
-	if(RNA_property_type(prop) == PROP_ENUM) {
+	if(RNA_property_type(prop) != PROP_ENUM) {
+		RNA_warning("uiItemsEnumR: not an enum property: %s.%s\n", RNA_struct_identifier(ptr->type), propname);
+		return;
+	}
+	else {
 		EnumPropertyItem *item;
 		int totitem, i, free;
 		uiLayout *split= uiLayoutSplit(layout, 0, 0);
@@ -1288,13 +1295,13 @@ void uiItemPointerR(uiLayout *layout, struct PointerRNA *ptr, const char *propna
 	prop= RNA_struct_find_property(ptr, propname);
 
 	if(!prop) {
-		printf("uiItemPointerR: property not found: %s.%s\n", RNA_struct_identifier(ptr->type), propname);
+		RNA_warning("uiItemPointerR: property not found: %s.%s\n", RNA_struct_identifier(ptr->type), propname);
 		return;
 	}
 	
 	type= RNA_property_type(prop);
 	if(!ELEM(type, PROP_POINTER, PROP_STRING)) {
-		printf("uiItemPointerR: property %s must be a pointer or string.\n", propname);
+		RNA_warning("uiItemPointerR: property %s must be a pointer or string.\n", propname);
 		return;
 	}
 
@@ -1302,11 +1309,11 @@ void uiItemPointerR(uiLayout *layout, struct PointerRNA *ptr, const char *propna
 
 
 	if(!searchprop) {
-		printf("uiItemPointerR: search collection property not found: %s.%s\n", RNA_struct_identifier(ptr->type), searchpropname);
+		RNA_warning("uiItemPointerR: search collection property not found: %s.%s\n", RNA_struct_identifier(ptr->type), searchpropname);
 		return;
 	}
 	else if (RNA_property_type(searchprop) != PROP_COLLECTION) {
-		printf("uiItemPointerR: search collection property is not a collection type: %s.%s\n", RNA_struct_identifier(ptr->type), searchpropname);
+		RNA_warning("uiItemPointerR: search collection property is not a collection type: %s.%s\n", RNA_struct_identifier(ptr->type), searchpropname);
 		return;
 	}
 
@@ -1391,7 +1398,7 @@ void uiItemM(uiLayout *layout, bContext *UNUSED(C), const char *menuname, const
 	mt= WM_menutype_find(menuname, FALSE);
 
 	if(mt==NULL) {
-		printf("uiItemM: not found %s\n", menuname);
+		RNA_warning("uiItemM: not found %s\n", menuname);
 		return;
 	}
 
@@ -1504,11 +1511,12 @@ static void menu_item_enum_opname_menu(bContext *UNUSED(C), uiLayout *layout, vo
 
 void uiItemMenuEnumO(uiLayout *layout, const char *opname, const char *propname, const char *name, int icon)
 {
-	wmOperatorType *ot= WM_operatortype_find(opname, 0);
+	wmOperatorType *ot= WM_operatortype_find(opname, 1);
 	MenuItemLevel *lvl;
 
 	if(!ot || !ot->srna) {
 		ui_item_disabled(layout, opname);
+		RNA_warning("uiItemMenuEnumO: %s '%s'\n", ot ? "unknown operator" : "operator missing srna", name);
 		return;
 	}
 
@@ -1541,6 +1549,7 @@ void uiItemMenuEnumR(uiLayout *layout, struct PointerRNA *ptr, const char *propn
 	prop= RNA_struct_find_property(ptr, propname);
 	if(!prop) {
 		ui_item_disabled(layout, propname);
+		RNA_warning("uiItemMenuEnumR: property not found: %s.%s\n", RNA_struct_identifier(ptr->type), propname);
 		return;
 	}
 
diff --git a/source/blender/editors/interface/interface_templates.c b/source/blender/editors/interface/interface_templates.c
index 5944d1606e1..d13de5cf0c6 100644
--- a/source/blender/editors/interface/interface_templates.c
+++ b/source/blender/editors/interface/interface_templates.c
@@ -240,7 +240,7 @@ static void template_id_cb(bContext *C, void *arg_litem, void *arg_event)
 	switch(event) {
 		case UI_ID_BROWSE:
 		case UI_ID_PIN:
-			printf("warning, id event %d shouldnt come here\n", event);
+			RNA_warning("warning, id event %d shouldnt come here\n", event);
 			break;
 		case UI_ID_OPEN:
 		case UI_ID_ADD_NEW:
@@ -484,7 +484,7 @@ static void ui_template_id(uiLayout *layout, bContext *C, PointerRNA *ptr, const
 	prop= RNA_struct_find_property(ptr, propname);
 
 	if(!prop || RNA_property_type(prop) != PROP_POINTER) {
-		printf("uiTemplateID: pointer property not found: %s.%s\n", RNA_struct_identifier(ptr->type), propname);
+		RNA_warning("uiTemplateID: pointer property not found: %s.%s\n", RNA_struct_identifier(ptr->type), propname);
 		return;
 	}
 
@@ -545,11 +545,11 @@ void uiTemplateAnyID(uiLayout *layout, PointerRNA *ptr, const char *propname, co
 	propType= RNA_struct_find_property(ptr, proptypename);
 
 	if (!propID || RNA_property_type(propID) != PROP_POINTER) {
-		printf("uiTemplateAnyID: pointer property not found: %s.%s\n", RNA_struct_identifier(ptr->type), propname);
+		RNA_warning("uiTemplateAnyID: pointer property not found: %s.%s\n", RNA_struct_identifier(ptr->type), propname);
 		return;
 	}
 	if (!propType || RNA_property_type(propType) != PROP_ENUM) { 
-		printf("uiTemplateAnyID: pointer-type property not found: %s.%s\n", RNA_struct_identifier(ptr->type), proptypename);
+		RNA_warning("uiTemplateAnyID: pointer-type property not found: %s.%s\n", RNA_struct_identifier(ptr->type), proptypename);
 		return;
 	}
 	
@@ -588,7 +588,7 @@ void uiTemplatePathBuilder(uiLayout *layout, PointerRNA *ptr, const char *propna
 	/* check that properties are valid */
 	propPath= RNA_struct_find_property(ptr, propname);
 	if (!propPath || RNA_property_type(propPath) != PROP_STRING) {
-		printf("uiTemplatePathBuilder: path property not found: %s.%s\n", RNA_struct_identifier(ptr->type), propname);
+		RNA_warning("uiTemplatePathBuilder: path property not found: %s.%s\n", RNA_struct_identifier(ptr->type), propname);
 		return;
 	}
 	
@@ -830,7 +830,7 @@ uiLayout *uiTemplateModifier(uiLayout *layout, bContext *C, PointerRNA *ptr)
 
 	/* verify we have valid data */
 	if(!RNA_struct_is_a(ptr->type, &RNA_Modifier)) {
-		printf("uiTemplateModifier: expected modifier on object.\n");
+		RNA_warning("uiTemplateModifier: expected modifier on object.\n");
 		return NULL;
 	}
 
@@ -838,7 +838,7 @@ uiLayout *uiTemplateModifier(uiLayout *layout, bContext *C, PointerRNA *ptr)
 	md= ptr->data;
 
 	if(!ob || !(GS(ob->id.name) == ID_OB)) {
-		printf("uiTemplateModifier: expected modifier on object.\n");
+		RNA_warning("uiTemplateModifier: expected modifier on object.\n");
 		return NULL;
 	}
 	
@@ -1062,7 +1062,7 @@ uiLayout *uiTemplateConstraint(uiLayout *layout, PointerRNA *ptr)
 
 	/* verify we have valid data */
 	if(!RNA_struct_is_a(ptr->type, &RNA_Constraint)) {
-		printf("uiTemplateConstraint: expected constraint on object.\n");
+		RNA_warning("uiTemplateConstraint: expected constraint on object.\n");
 		return NULL;
 	}
 
@@ -1070,7 +1070,7 @@ uiLayout *uiTemplateConstraint(uiLayout *layout, PointerRNA *ptr)
 	con= ptr->data;
 
 	if(!ob || !(GS(ob->id.name) == ID_OB)) {
-		printf("uiTemplateConstraint: expected constraint on object.\n");
+		RNA_warning("uiTemplateConstraint: expected constraint on object.\n");
 		return NULL;
 	}
 	
@@ -1116,7 +1116,7 @@ void uiTemplatePreview(uiLayout *layout, ID *id, int show_buttons, ID *parent, M
 	PointerRNA texture_ptr;
 
 	if(id && !ELEM4(GS(id->name), ID_MA, ID_TE, ID_WO, ID_LA)) {
-		printf("uiTemplatePreview: expected ID of type material, texture, lamp or world.\n");
+		RNA_warning("uiTemplatePreview: expected ID of type material, texture, lamp or world.\n");
 		return;
 	}
 
@@ -1818,8 +1818,15 @@ void uiTemplateCurveMapping(uiLayout *layout, PointerRNA *ptr, const char *propn
 	PropertyRNA *prop= RNA_struct_find_property(ptr, propname);
 	PointerRNA cptr;
 
-	if(!prop || RNA_property_type(prop) != PROP_POINTER)
+	if(!prop) {
+		RNA_warning("uiTemplateCurveMapping: curve property not found: %s.%s\n", RNA_struct_identifier(ptr->type), propname);
 		return;
+	}
+
+	if(RNA_property_type(prop) != PROP_POINTER) {
+		RNA_warning("uiTemplateCurveMapping: curve is not a pointer: %s.%s\n", RNA_struct_identifier(ptr->type), propname);
+		return;
+	}
 
 	cptr= RNA_property_pointer_get(ptr, prop);
 	if(!cptr.data || !RNA_struct_is_a(cptr.type, &RNA_CurveMapping))
@@ -1847,7 +1854,7 @@ void uiTemplateColorWheel(uiLayout *layout, PointerRNA *ptr, const char *propnam
 	float softmin, softmax, step, precision;
 	
 	if (!prop) {
-		printf("uiTemplateColorWheel: property not found: %s.%s\n", RNA_struct_identifier(ptr->type), propname);
+		RNA_warning("uiTemplateColorWheel: property not found: %s.%s\n", RNA_struct_identifier(ptr->type), propname);
 		return;
 	}
 
@@ -1917,7 +1924,7 @@ void uiTemplateLayers(uiLayout *layout, PointerRNA *ptr, const char *propname,
 
 	prop= RNA_struct_find_property(ptr, propname);
 	if (!prop) {
-		printf("uiTemplateLayer: layers property not found: %s.%s\n", RNA_struct_identifier(ptr->type), propname);
+		RNA_warning("uiTemplateLayer: layers property not found: %s.%s\n", RNA_struct_identifier(ptr->type), propname);
 		return;
 	}
 	
@@ -1934,7 +1941,7 @@ void uiTemplateLayers(uiLayout *layout, PointerRNA *ptr, const char *propname,
 	if(used_ptr && used_propname) {
 		used_prop= RNA_struct_find_property(used_ptr, used_propname);
 		if (!used_prop) {
-			printf("uiTemplateLayer: used layers property not found: %s.%s\n", RNA_struct_identifier(ptr->type), used_propname);
+			RNA_warning("uiTemplateLayer: used layers property not found: %s.%s\n", RNA_struct_identifier(ptr->type), used_propname);
 			return;
 		}
 
@@ -2115,7 +2122,7 @@ void uiTemplateList(uiLayout *layout, bContext *C, PointerRNA *ptr, const char *
 	pa= block->panel;
 
 	if(!pa) {
-		printf("uiTemplateList: only works inside a panel.\n");
+		RNA_warning("uiTemplateList: only works inside a panel.\n");
 		return;
 	}
 
@@ -2125,28 +2132,28 @@ void uiTemplateList(uiLayout *layout, bContext *C, PointerRNA *ptr, const char *
 	if(ptr->data) {
 		prop= RNA_struct_find_property(ptr, propname);
 		if(!prop) {
-			printf("uiTemplateList: property not found: %s.%s\n", RNA_struct_identifier(ptr->type), propname);
+			RNA_warning("uiTemplateList: property not found: %s.%s\n", RNA_struct_identifier(ptr->type), propname);
 			return;
 		}
 	}
 
 	activeprop= RNA_struct_find_property(activeptr, activepropname);
 	if(!activeprop) {
-		printf("uiTemplateList: property not found: %s.%s\n", RNA_struct_identifier(ptr->type), activepropname);
+		RNA_warning("uiTemplateList: property not found: %s.%s\n", RNA_struct_identifier(ptr->type), activepropname);
 		return;
 	}
 
 	if(prop) {
 		type= RNA_property_type(prop);
 		if(type != PROP_COLLECTION) {
-			printf("uiTemplateList: expected collection property.\n");
+			RNA_warning("uiTemplateList: expected collection property.\n");
 			return;
 		}
 	}
 
 	activetype= RNA_property_type(activeprop);
 	if(activetype != PROP_INT) {
-		printf("uiTemplateList: expected integer property.\n");
+		RNA_warning("uiTemplateList: expected integer property.\n");
 		return;
 	}
 
diff --git a/source/blender/makesrna/RNA_access.h b/source/blender/makesrna/RNA_access.h
index 076aa199766..e67728def11 100644
--- a/source/blender/makesrna/RNA_access.h
+++ b/source/blender/makesrna/RNA_access.h
@@ -955,6 +955,12 @@ int RNA_function_call_direct_va_lookup(struct bContext *C, struct ReportList *re
 short RNA_type_to_ID_code(StructRNA *type);
 StructRNA *ID_code_to_RNA_type(short idcode);
 
+void RNA_warning(const char *format, ...)
+#ifdef __GNUC__
+__attribute__ ((format (printf, 1, 2)))
+#endif
+;
+
 #ifdef __cplusplus
 }
 #endif
diff --git a/source/blender/makesrna/intern/rna_access.c b/source/blender/makesrna/intern/rna_access.c
index cd243d49fde..cbd02d885dc 100644
--- a/source/blender/makesrna/intern/rna_access.c
+++ b/source/blender/makesrna/intern/rna_access.c
@@ -62,6 +62,22 @@
 
 #include "rna_internal.h"
 
+void RNA_warning(const char *format, ...)
+{
+	va_list args;
+
+	va_start(args, format);
+	vprintf(format, args);
+	va_end(args);
+
+#if WITH_PYTHON
+	{
+		extern void PyC_LineSpit(void);
+		PyC_LineSpit();
+	}
+#endif
+}
+
 const PointerRNA PointerRNA_NULL= {{NULL}};
 
 /* Init/Exit */
diff --git a/source/blender/python/generic/py_capi_utils.c b/source/blender/python/generic/py_capi_utils.c
index fd44e09003e..7182d5f75d0 100644
--- a/source/blender/python/generic/py_capi_utils.c
+++ b/source/blender/python/generic/py_capi_utils.c
@@ -30,6 +30,8 @@
 
 #include "py_capi_utils.h"
 
+#define PYC_INTERPRETER_ACTIVE (((PyThreadState*)_Py_atomic_load_relaxed(&_PyThreadState_Current)) != NULL)
+
 /* for debugging */
 void PyC_ObSpit(const char *name, PyObject *var) {
 	fprintf(stderr, "<%s> : ", name);
@@ -51,9 +53,16 @@ void PyC_ObSpit(const char *name, PyObject *var) {
 }
 
 void PyC_LineSpit(void) {
+
 	const char *filename;
 	int lineno;
 
+	/* Note, allow calling from outside python (RNA) */
+	if(!PYC_INTERPRETER_ACTIVE) {
+		fprintf(stderr, "python line lookup failed, interpreter inactive\n");
+		return;
+	}
+
 	PyErr_Clear();
 	PyC_FileAndNum(&filename, &lineno);
 	
diff --git a/source/blender/python/generic/py_capi_utils.h b/source/blender/python/generic/py_capi_utils.h
index c78e78b5a0b..0b821759bec 100644
--- a/source/blender/python/generic/py_capi_utils.h
+++ b/source/blender/python/generic/py_capi_utils.h
@@ -47,4 +47,5 @@ void			PyC_RunQuicky(const char *filepath, int n, ...);
 
 void PyC_MainModule_Backup(PyObject **main_mod);
 void PyC_MainModule_Restore(PyObject *main_mod);
+
 #endif // PY_CAPI_UTILS_H