WM: pass on wmDrag to drop operators, so they can get the data directly.

Currently drop operators work mostly by specifying the name of the datablock.
However there can be datablocks with the same name in different libraries, so
this gives wrong results in some cases.

Currently only outliner drop operators have been updated to use this mechanism.

8 files changed, 324 insertions, 487 deletions

diff --git a/source/blender/editors/space_console/space_console.c b/source/blender/editors/space_console/space_console.c
index ce87ad3b177..3429d726349 100644
--- a/source/blender/editors/space_console/space_console.c
+++ b/source/blender/editors/space_console/space_console.c
@@ -172,29 +172,22 @@ static void console_cursor(wmWindow *win, ScrArea *sa, ARegion *ar)
 
 static bool id_drop_poll(bContext *UNUSED(C), wmDrag *drag, const wmEvent *UNUSED(event), const char **UNUSED(tooltip))
 {
-//	SpaceConsole *sc = CTX_wm_space_console(C);
-	if (drag->type == WM_DRAG_ID)
-		return 1;
-	return 0;
+	return WM_drag_ID(drag, 0) != NULL;
 }
 
 static void id_drop_copy(wmDrag *drag, wmDropBox *drop)
 {
-	char *text;
-	ID *id = drag->poin;
+	ID *id = WM_drag_ID(drag, 0);
 
 	/* copy drag path to properties */
-	text = RNA_path_full_ID_py(id);
+	char *text = RNA_path_full_ID_py(id);
 	RNA_string_set(drop->ptr, "text", text);
 	MEM_freeN(text);
 }
 
 static bool path_drop_poll(bContext *UNUSED(C), wmDrag *drag, const wmEvent *UNUSED(event), const char **UNUSED(tooltip))
 {
-	// SpaceConsole *sc = CTX_wm_space_console(C);
-	if (drag->type == WM_DRAG_PATH)
-		return 1;
-	return 0;
+	return (drag->type == WM_DRAG_PATH);
 }
 
 static void path_drop_copy(wmDrag *drag, wmDropBox *drop)
diff --git a/source/blender/editors/space_node/space_node.c b/source/blender/editors/space_node/space_node.c
index 74c036883e6..2b2e659d151 100644
--- a/source/blender/editors/space_node/space_node.c
+++ b/source/blender/editors/space_node/space_node.c
@@ -677,26 +677,17 @@ static void node_main_region_draw(const bContext *C, ARegion *ar)
 
 static bool node_ima_drop_poll(bContext *UNUSED(C), wmDrag *drag, const wmEvent *UNUSED(event), const char **UNUSED(tooltip))
 {
-	if (drag->type == WM_DRAG_ID) {
-		ID *id = drag->poin;
-		if (GS(id->name) == ID_IM)
-			return 1;
+	if (drag->type == WM_DRAG_PATH) {
+		return (ELEM(drag->icon, 0, ICON_FILE_IMAGE, ICON_FILE_MOVIE));   /* rule might not work? */
 	}
-	else if (drag->type == WM_DRAG_PATH) {
-		if (ELEM(drag->icon, 0, ICON_FILE_IMAGE, ICON_FILE_MOVIE))   /* rule might not work? */
-			return 1;
+	else {
+		return WM_drag_ID(drag, ID_IM) != NULL;
 	}
-	return 0;
 }
 
 static bool node_mask_drop_poll(bContext *UNUSED(C), wmDrag *drag, const wmEvent *UNUSED(event), const char **UNUSED(tooltip))
 {
-	if (drag->type == WM_DRAG_ID) {
-		ID *id = drag->poin;
-		if (GS(id->name) == ID_MSK)
-			return 1;
-	}
-	return 0;
+	return WM_drag_ID(drag, ID_MSK) != NULL;
 }
 
 static void node_id_drop_copy(wmDrag *drag, wmDropBox *drop)
diff --git a/source/blender/editors/space_outliner/outliner_dragdrop.c b/source/blender/editors/space_outliner/outliner_dragdrop.c
index c53a431a017..f9a4fda0c45 100644
--- a/source/blender/editors/space_outliner/outliner_dragdrop.c
+++ b/source/blender/editors/space_outliner/outliner_dragdrop.c
@@ -39,6 +39,7 @@
 #include "DNA_space_types.h"
 
 #include "BLI_listbase.h"
+#include "BLI_string.h"
 
 #include "BLT_translation.h"
 
@@ -105,64 +106,77 @@ static TreeElement *outliner_dropzone_find(const SpaceOops *soops, const float f
 	return NULL;
 }
 
-/* ******************** Parent Drop Operator *********************** */
-
-static bool parent_drop_poll(bContext *C, wmDrag *drag, const wmEvent *event, const char **UNUSED(tooltip))
+static TreeElement *outliner_drop_find(bContext *C, const wmEvent *event)
 {
 	ARegion *ar = CTX_wm_region(C);
 	SpaceOops *soops = CTX_wm_space_outliner(C);
 	float fmval[2];
 	UI_view2d_region_to_view(&ar->v2d, event->mval[0], event->mval[1], &fmval[0], &fmval[1]);
 
-	if (drag->type == WM_DRAG_ID) {
-		ID *id = drag->poin;
-		if (GS(id->name) == ID_OB) {
-			/* Ensure item under cursor is valid drop target */
-			TreeElement *te = outliner_dropzone_find(soops, fmval, true);
-			TreeStoreElem *tselem = te ? TREESTORE(te) : NULL;
+	return outliner_dropzone_find(soops, fmval, true);
+}
 
-			if (!te) {
-				/* pass */
-			}
-			else if (te->idcode == ID_OB && tselem->type == 0) {
-				Scene *scene;
-				ID *te_id = tselem->id;
-
-				/* check if dropping self or parent */
-				if (te_id == id || (Object *)te_id == ((Object *)id)->parent)
-					return 0;
-
-				/* check that parent/child are both in the same scene */
-				scene = (Scene *)outliner_search_back(soops, te, ID_SCE);
-
-				/* currently outliner organized in a way that if there's no parent scene
-				 * element for object it means that all displayed objects belong to
-				 * active scene and parenting them is allowed (sergey)
-				 */
-				if (!scene) {
-					return 1;
-				}
-				else {
-					for (ViewLayer *view_layer = scene->view_layers.first;
-					     view_layer;
-					     view_layer = view_layer->next)
-					{
-						if (BKE_view_layer_base_find(view_layer, (Object *)id)) {
-							return 1;
-						}
-					}
-				}
-			}
-		}
+static ID *outliner_ID_drop_find(bContext *C, const wmEvent *event, short idcode)
+{
+	TreeElement *te = outliner_drop_find(C, event);
+	TreeStoreElem *tselem = (te) ? TREESTORE(te) : NULL;
+
+	if (te && te->idcode == idcode && tselem->type == 0) {
+		return tselem->id;
+	}
+	else {
+		return NULL;
 	}
-	return 0;
 }
 
-static void parent_drop_copy(wmDrag *drag, wmDropBox *drop)
+/* ******************** Parent Drop Operator *********************** */
+
+static bool parent_drop_poll(bContext *C, wmDrag *drag, const wmEvent *event, const char **UNUSED(tooltip))
 {
-	ID *id = drag->poin;
+	SpaceOops *soops = CTX_wm_space_outliner(C);
+	Object *ob = (Object *)WM_drag_ID(drag, ID_OB);
+	if (!ob) {
+		return false;
+	}
+
+	/* Ensure item under cursor is valid drop target */
+	TreeElement *te = outliner_drop_find(C, event);
+	TreeStoreElem *tselem = te ? TREESTORE(te) : NULL;
+
+	if (!te) {
+		/* pass */
+	}
+	else if (te->idcode == ID_OB && tselem->type == 0) {
+		Scene *scene;
+		ID *te_id = tselem->id;
+
+		/* check if dropping self or parent */
+		if (te_id == &ob->id || (Object *)te_id == ob->parent)
+			return false;
+
+		/* check that parent/child are both in the same scene */
+		scene = (Scene *)outliner_search_back(soops, te, ID_SCE);
+
+		/* currently outliner organized in a way that if there's no parent scene
+		 * element for object it means that all displayed objects belong to
+		 * active scene and parenting them is allowed (sergey)
+		 */
+		if (!scene) {
+			return true;
+		}
+		else {
+			for (ViewLayer *view_layer = scene->view_layers.first;
+				 view_layer;
+				 view_layer = view_layer->next)
+			{
+				if (BKE_view_layer_base_find(view_layer, ob)) {
+					return true;
+				}
+			}
+		}
+	}
 
-	RNA_string_set(drop->ptr, "child", id->name + 2);
+	return false;
 }
 
 static int parent_drop_exec(bContext *C, wmOperator *op)
@@ -195,131 +209,121 @@ static int parent_drop_exec(bContext *C, wmOperator *op)
 
 static int parent_drop_invoke(bContext *C, wmOperator *op, const wmEvent *event)
 {
-	Object *par = NULL;
-	Object *ob = NULL;
-	SpaceOops *soops = CTX_wm_space_outliner(C);
-	ARegion *ar = CTX_wm_region(C);
 	Main *bmain = CTX_data_main(C);
-	Scene *scene = NULL;
-	TreeElement *te = NULL;
+	SpaceOops *soops = CTX_wm_space_outliner(C);
+	TreeElement *te = outliner_drop_find(C, event);
+	TreeStoreElem *tselem = te ? TREESTORE(te) : NULL;
+
+	if (!(te && te->idcode == ID_OB && tselem->type == 0)) {
+		return OPERATOR_CANCELLED;
+	}
+
+	Object *par = (Object *)tselem->id;
+	Object *ob = (Object *)WM_drag_ID_from_event(event, ID_OB);
+
+	if (ELEM(NULL, ob, par)) {
+		return OPERATOR_CANCELLED;
+	}
+	if (ob == par) {
+		return OPERATOR_CANCELLED;
+	}
+	if (ID_IS_LINKED(ob)) {
+		BKE_report(op->reports, RPT_INFO, "Can't edit library linked object");
+		return OPERATOR_CANCELLED;
+	}
+
 	char childname[MAX_ID_NAME];
 	char parname[MAX_ID_NAME];
-	int partype = 0;
-	float fmval[2];
+	STRNCPY(childname, ob->id.name);
+	STRNCPY(parname, par->id.name);
+	RNA_string_set(op->ptr, "child", childname);
+	RNA_string_set(op->ptr, "parent", parname);
 
-	UI_view2d_region_to_view(&ar->v2d, event->mval[0], event->mval[1], &fmval[0], &fmval[1]);
+	Scene *scene = (Scene *)outliner_search_back(soops, te, ID_SCE);
 
-	/* Find object hovered over */
-	te = outliner_dropzone_find(soops, fmval, true);
+	if (scene == NULL) {
+		/* currently outlier organized in a way, that if there's no parent scene
+		 * element for object it means that all displayed objects belong to
+		 * active scene and parenting them is allowed (sergey)
+		 */
 
-	if (te) {
-		RNA_string_set(op->ptr, "parent", te->name);
-		/* Identify parent and child */
-		RNA_string_get(op->ptr, "child", childname);
-		ob = (Object *)BKE_libblock_find_name(bmain, ID_OB, childname);
-		RNA_string_get(op->ptr, "parent", parname);
-		par = (Object *)BKE_libblock_find_name(bmain, ID_OB, parname);
-
-		if (ELEM(NULL, ob, par)) {
-			if (par == NULL) printf("par==NULL\n");
-			return OPERATOR_CANCELLED;
-		}
-		if (ob == par) {
-			return OPERATOR_CANCELLED;
-		}
-		if (ID_IS_LINKED(ob)) {
-			BKE_report(op->reports, RPT_INFO, "Can't edit library linked object");
-			return OPERATOR_CANCELLED;
+		scene = CTX_data_scene(C);
+	}
+
+	if ((par->type != OB_ARMATURE) && (par->type != OB_CURVE) && (par->type != OB_LATTICE)) {
+		int partype = 0;
+		if (ED_object_parent_set(op->reports, C, scene, ob, par, partype, false, false, NULL)) {
+			DEG_relations_tag_update(bmain);
+			WM_event_add_notifier(C, NC_OBJECT | ND_TRANSFORM, NULL);
+			WM_event_add_notifier(C, NC_OBJECT | ND_PARENT, NULL);
 		}
+	}
+	else {
+		/* Menu creation */
+		wmOperatorType *ot = WM_operatortype_find("OUTLINER_OT_parent_drop", false);
+		uiPopupMenu *pup = UI_popup_menu_begin(C, IFACE_("Set Parent To"), ICON_NONE);
+		uiLayout *layout = UI_popup_menu_layout(pup);
+		PointerRNA ptr;
+
+		/* Cannot use uiItemEnumO()... have multiple properties to set. */
+		uiItemFullO_ptr(layout, ot, IFACE_("Object"), 0, NULL, WM_OP_EXEC_DEFAULT, 0, &ptr);
+		RNA_string_set(&ptr, "parent", parname);
+		RNA_string_set(&ptr, "child", childname);
+		RNA_enum_set(&ptr, "type", PAR_OBJECT);
+
+		/* par becomes parent, make the associated menus */
+		if (par->type == OB_ARMATURE) {
+			uiItemFullO_ptr(layout, ot, IFACE_("Armature Deform"), 0, NULL, WM_OP_EXEC_DEFAULT, 0, &ptr);
+			RNA_string_set(&ptr, "parent", parname);
+			RNA_string_set(&ptr, "child", childname);
+			RNA_enum_set(&ptr, "type", PAR_ARMATURE);
 
-		scene = (Scene *)outliner_search_back(soops, te, ID_SCE);
+			uiItemFullO_ptr(layout, ot, IFACE_("   With Empty Groups"), 0, NULL, WM_OP_EXEC_DEFAULT, 0, &ptr);
+			RNA_string_set(&ptr, "parent", parname);
+			RNA_string_set(&ptr, "child", childname);
+			RNA_enum_set(&ptr, "type", PAR_ARMATURE_NAME);
 
-		if (scene == NULL) {
-			/* currently outlier organized in a way, that if there's no parent scene
-			 * element for object it means that all displayed objects belong to
-			 * active scene and parenting them is allowed (sergey)
-			 */
+			uiItemFullO_ptr(layout, ot, IFACE_("   With Envelope Weights"), 0, NULL, WM_OP_EXEC_DEFAULT, 0, &ptr);
+			RNA_string_set(&ptr, "parent", parname);
+			RNA_string_set(&ptr, "child", childname);
+			RNA_enum_set(&ptr, "type", PAR_ARMATURE_ENVELOPE);
 
-			scene = CTX_data_scene(C);
-		}
+			uiItemFullO_ptr(layout, ot, IFACE_("   With Automatic Weights"), 0, NULL, WM_OP_EXEC_DEFAULT, 0, &ptr);
+			RNA_string_set(&ptr, "parent", parname);
+			RNA_string_set(&ptr, "child", childname);
+			RNA_enum_set(&ptr, "type", PAR_ARMATURE_AUTO);
 
-		if ((par->type != OB_ARMATURE) && (par->type != OB_CURVE) && (par->type != OB_LATTICE)) {
-			if (ED_object_parent_set(op->reports, C, scene, ob, par, partype, false, false, NULL)) {
-				DEG_relations_tag_update(bmain);
-				WM_event_add_notifier(C, NC_OBJECT | ND_TRANSFORM, NULL);
-				WM_event_add_notifier(C, NC_OBJECT | ND_PARENT, NULL);
-			}
+			uiItemFullO_ptr(layout, ot, IFACE_("Bone"), 0, NULL, WM_OP_EXEC_DEFAULT, 0, &ptr);
+			RNA_string_set(&ptr, "parent", parname);
+			RNA_string_set(&ptr, "child", childname);
+			RNA_enum_set(&ptr, "type", PAR_BONE);
 		}
-		else {
-			/* Menu creation */
-			wmOperatorType *ot = WM_operatortype_find("OUTLINER_OT_parent_drop", false);
-			uiPopupMenu *pup = UI_popup_menu_begin(C, IFACE_("Set Parent To"), ICON_NONE);
-			uiLayout *layout = UI_popup_menu_layout(pup);
-			PointerRNA ptr;
-
-			/* Cannot use uiItemEnumO()... have multiple properties to set. */
-			uiItemFullO_ptr(layout, ot, IFACE_("Object"), 0, NULL, WM_OP_EXEC_DEFAULT, 0, &ptr);
+		else if (par->type == OB_CURVE) {
+			uiItemFullO_ptr(layout, ot, IFACE_("Curve Deform"), 0, NULL, WM_OP_EXEC_DEFAULT, 0, &ptr);
 			RNA_string_set(&ptr, "parent", parname);
 			RNA_string_set(&ptr, "child", childname);
-			RNA_enum_set(&ptr, "type", PAR_OBJECT);
-
-			/* par becomes parent, make the associated menus */
-			if (par->type == OB_ARMATURE) {
-				uiItemFullO_ptr(layout, ot, IFACE_("Armature Deform"), 0, NULL, WM_OP_EXEC_DEFAULT, 0, &ptr);
-				RNA_string_set(&ptr, "parent", parname);
-				RNA_string_set(&ptr, "child", childname);
-				RNA_enum_set(&ptr, "type", PAR_ARMATURE);
-
-				uiItemFullO_ptr(layout, ot, IFACE_("   With Empty Groups"), 0, NULL, WM_OP_EXEC_DEFAULT, 0, &ptr);
-				RNA_string_set(&ptr, "parent", parname);
-				RNA_string_set(&ptr, "child", childname);
-				RNA_enum_set(&ptr, "type", PAR_ARMATURE_NAME);
-
-				uiItemFullO_ptr(layout, ot, IFACE_("   With Envelope Weights"), 0, NULL, WM_OP_EXEC_DEFAULT, 0, &ptr);
-				RNA_string_set(&ptr, "parent", parname);
-				RNA_string_set(&ptr, "child", childname);
-				RNA_enum_set(&ptr, "type", PAR_ARMATURE_ENVELOPE);
-
-				uiItemFullO_ptr(layout, ot, IFACE_("   With Automatic Weights"), 0, NULL, WM_OP_EXEC_DEFAULT, 0, &ptr);
-				RNA_string_set(&ptr, "parent", parname);
-				RNA_string_set(&ptr, "child", childname);
-				RNA_enum_set(&ptr, "type", PAR_ARMATURE_AUTO);
-
-				uiItemFullO_ptr(layout, ot, IFACE_("Bone"), 0, NULL, WM_OP_EXEC_DEFAULT, 0, &ptr);
-				RNA_string_set(&ptr, "parent", parname);
-				RNA_string_set(&ptr, "child", childname);
-				RNA_enum_set(&ptr, "type", PAR_BONE);
-			}
-			else if (par->type == OB_CURVE) {
-				uiItemFullO_ptr(layout, ot, IFACE_("Curve Deform"), 0, NULL, WM_OP_EXEC_DEFAULT, 0, &ptr);
-				RNA_string_set(&ptr, "parent", parname);
-				RNA_string_set(&ptr, "child", childname);
-				RNA_enum_set(&ptr, "type", PAR_CURVE);
-
-				uiItemFullO_ptr(layout, ot, IFACE_("Follow Path"), 0, NULL, WM_OP_EXEC_DEFAULT, 0, &ptr);
-				RNA_string_set(&ptr, "parent", parname);
-				RNA_string_set(&ptr, "child", childname);
-				RNA_enum_set(&ptr, "type", PAR_FOLLOW);
-
-				uiItemFullO_ptr(layout, ot, IFACE_("Path Constraint"), 0, NULL, WM_OP_EXEC_DEFAULT, 0, &ptr);
-				RNA_string_set(&ptr, "parent", parname);
-				RNA_string_set(&ptr, "child", childname);
-				RNA_enum_set(&ptr, "type", PAR_PATH_CONST);
-			}
-			else if (par->type == OB_LATTICE) {
-				uiItemFullO_ptr(layout, ot, IFACE_("Lattice Deform"), 0, NULL, WM_OP_EXEC_DEFAULT, 0, &ptr);
-				RNA_string_set(&ptr, "parent", parname);
-				RNA_string_set(&ptr, "child", childname);
-				RNA_enum_set(&ptr, "type", PAR_LATTICE);
-			}
+			RNA_enum_set(&ptr, "type", PAR_CURVE);
 
-			UI_popup_menu_end(C, pup);
+			uiItemFullO_ptr(layout, ot, IFACE_("Follow Path"), 0, NULL, WM_OP_EXEC_DEFAULT, 0, &ptr);
+			RNA_string_set(&ptr, "parent", parname);
+			RNA_string_set(&ptr, "child", childname);
+			RNA_enum_set(&ptr, "type", PAR_FOLLOW);
 
-			return OPERATOR_INTERFACE;
+			uiItemFullO_ptr(layout, ot, IFACE_("Path Constraint"), 0, NULL, WM_OP_EXEC_DEFAULT, 0, &ptr);
+			RNA_string_set(&ptr, "parent", parname);
+			RNA_string_set(&ptr, "child", childname);
+			RNA_enum_set(&ptr, "type", PAR_PATH_CONST);
 		}
-	}
-	else {
-		return OPERATOR_CANCELLED;
+		else if (par->type == OB_LATTICE) {
+			uiItemFullO_ptr(layout, ot, IFACE_("Lattice Deform"), 0, NULL, WM_OP_EXEC_DEFAULT, 0, &ptr);
+			RNA_string_set(&ptr, "parent", parname);
+			RNA_string_set(&ptr, "child", childname);
+			RNA_enum_set(&ptr, "type", PAR_LATTICE);
+		}
+
+		UI_popup_menu_end(C, pup);
+
+		return OPERATOR_INTERFACE;
 	}
 
 	return OPERATOR_FINISHED;
@@ -369,64 +373,42 @@ static bool parenting_poll(bContext *C)
 
 static bool parent_clear_poll(bContext *C, wmDrag *drag, const wmEvent *event, const char **UNUSED(tooltip))
 {
-	ARegion *ar = CTX_wm_region(C);
 	SpaceOops *soops = CTX_wm_space_outliner(C);
-	TreeElement *te = NULL;
-	float fmval[2];
-
-	UI_view2d_region_to_view(&ar->v2d, event->mval[0], event->mval[1], &fmval[0], &fmval[1]);
 
 	if (!ELEM(soops->outlinevis, SO_VIEW_LAYER)) {
 		return false;
 	}
 
-	if (drag->type == WM_DRAG_ID) {
-		ID *id = drag->poin;
-		if (GS(id->name) == ID_OB) {
-			if (((Object *)id)->parent) {
-				if ((te = outliner_dropzone_find(soops, fmval, true))) {
-					TreeStoreElem *tselem = TREESTORE(te);
-
-					switch (te->idcode) {
-						case ID_SCE:
-							return (ELEM(tselem->type, TSE_R_LAYER_BASE, TSE_R_LAYER));
-						case ID_OB:
-							return (ELEM(tselem->type, TSE_MODIFIER_BASE, TSE_CONSTRAINT_BASE));
-						/* Other codes to ignore? */
-					}
-				}
-				return (te == NULL);
-			}
-		}
+	Object *ob = (Object *)WM_drag_ID(drag, ID_OB);
+	if (!(ob && ob->parent)) {
+		return false;
 	}
-	return 0;
-}
-
-static void parent_clear_copy(wmDrag *drag, wmDropBox *drop)
-{
-	ID *id = drag->poin;
-	RNA_string_set(drop->ptr, "dragged_obj", id->name + 2);
 
-	/* Set to simple parent clear type. Avoid menus for drag and drop if possible.
-	 * If desired, user can toggle the different "Clear Parent" types in the operator
-	 * menu on tool shelf. */
-	RNA_enum_set(drop->ptr, "type", 0);
+	TreeElement *te = outliner_drop_find(C, event);
+	if (te) {
+		TreeStoreElem *tselem = TREESTORE(te);
+
+		switch (te->idcode) {
+			case ID_SCE:
+				return (ELEM(tselem->type, TSE_R_LAYER_BASE, TSE_R_LAYER));
+			case ID_OB:
+				return (ELEM(tselem->type, TSE_MODIFIER_BASE, TSE_CONSTRAINT_BASE));
+			/* Other codes to ignore? */
+		}
+	}
+	return (te == NULL);
 }
 
-static int parent_clear_invoke(bContext *C, wmOperator *op, const wmEvent *UNUSED(event))
+static int parent_clear_invoke(bContext *C, wmOperator *UNUSED(op), const wmEvent *event)
 {
 	Main *bmain = CTX_data_main(C);
-	Object *ob = NULL;
-	SpaceOops *soops = CTX_wm_space_outliner(C);
-	char obname[MAX_ID_NAME];
+	Object *ob = (Object *)WM_drag_ID_from_event(event, ID_OB);
 
-	RNA_string_get(op->ptr, "dragged_obj", obname);
-	ob = (Object *)BKE_libblock_find_name(bmain, ID_OB, obname);
-
-	/* search forwards to find the object */
-	outliner_find_id(soops, &soops->tree, (ID *)ob);
+	if (ob == NULL) {
+		return OPERATOR_CANCELLED;
+	}
 
-	ED_object_parent_clear(ob, RNA_enum_get(op->ptr, "type"));
+	ED_object_parent_clear(ob, 0);
 
 	DEG_relations_tag_update(bmain);
 	WM_event_add_notifier(C, NC_OBJECT | ND_TRANSFORM, NULL);
@@ -448,97 +430,55 @@ void OUTLINER_OT_parent_clear(wmOperatorType *ot)
 
 	/* flags */
 	ot->flag = OPTYPE_REGISTER | OPTYPE_UNDO | OPTYPE_INTERNAL;
-
-	/* properties */
-	RNA_def_string(ot->srna, "dragged_obj", "Object", MAX_ID_NAME, "Child", "Child Object");
-	RNA_def_enum(ot->srna, "type", prop_clear_parent_types, 0, "Type", "");
 }
 
 /* ******************** Scene Drop Operator *********************** */
 
 static bool scene_drop_poll(bContext *C, wmDrag *drag, const wmEvent *event, const char **UNUSED(tooltip))
 {
-	ARegion *ar = CTX_wm_region(C);
-	SpaceOops *soops = CTX_wm_space_outliner(C);
-	float fmval[2];
-	UI_view2d_region_to_view(&ar->v2d, event->mval[0], event->mval[1], &fmval[0], &fmval[1]);
-
-	if (drag->type == WM_DRAG_ID) {
-		ID *id = drag->poin;
-		if (GS(id->name) == ID_OB) {
-			/* Ensure item under cursor is valid drop target */
-			TreeElement *te = outliner_dropzone_find(soops, fmval, false);
-			return (te && te->idcode == ID_SCE && TREESTORE(te)->type == 0);
-		}
-	}
-	return 0;
-}
-
-static void scene_drop_copy(wmDrag *drag, wmDropBox *drop)
-{
-	ID *id = drag->poin;
-
-	RNA_string_set(drop->ptr, "object", id->name + 2);
+	/* Ensure item under cursor is valid drop target */
+	Object *ob = (Object *)WM_drag_ID(drag, ID_OB);
+	return (ob && (outliner_ID_drop_find(C, event, ID_SCE) != NULL));
 }
 
-static int scene_drop_invoke(bContext *C, wmOperator *op, const wmEvent *event)
+static int scene_drop_invoke(bContext *C, wmOperator *UNUSED(op), const wmEvent *event)
 {
-	Scene *scene = NULL;
-	Object *ob = NULL;
-	SpaceOops *soops = CTX_wm_space_outliner(C);
-	ARegion *ar = CTX_wm_region(C);
 	Main *bmain = CTX_data_main(C);
-	TreeElement *te = NULL;
-	char obname[MAX_ID_NAME];
-	float fmval[2];
-
-	UI_view2d_region_to_view(&ar->v2d, event->mval[0], event->mval[1], &fmval[0], &fmval[1]);
-
-	/* Find object hovered over */
-	te = outliner_dropzone_find(soops, fmval, false);
+	Scene *scene = (Scene *)outliner_ID_drop_find(C, event, ID_SCE);
+	Object *ob = (Object *)WM_drag_ID_from_event(event, ID_OB);
 
-	if (te) {
-		RNA_string_set(op->ptr, "scene", te->name);
-		scene = (Scene *)BKE_libblock_find_name(bmain, ID_SCE, te->name);
-
-		RNA_string_get(op->ptr, "object", obname);
-		ob = (Object *)BKE_libblock_find_name(bmain, ID_OB, obname);
-
-		if (ELEM(NULL, ob, scene) || ID_IS_LINKED(scene)) {
-			return OPERATOR_CANCELLED;
-		}
+	if (ELEM(NULL, ob, scene) || ID_IS_LINKED(scene)) {
+		return OPERATOR_CANCELLED;
+	}
 
-		if (BKE_scene_has_object(scene, ob)) {
-			return OPERATOR_CANCELLED;
-		}
+	if (BKE_scene_has_object(scene, ob)) {
+		return OPERATOR_CANCELLED;
+	}
 
-		Collection *collection;
-		if (scene != CTX_data_scene(C)) {
-			/* when linking to an inactive scene link to the master collection */
-			collection = BKE_collection_master(scene);
-		}
-		else {
-			collection = CTX_data_collection(C);
-		}
+	Collection *collection;
+	if (scene != CTX_data_scene(C)) {
+		/* when linking to an inactive scene link to the master collection */
+		collection = BKE_collection_master(scene);
+	}
+	else {
+		collection = CTX_data_collection(C);
+	}
 
-		BKE_collection_object_add(bmain, collection, ob);
+	BKE_collection_object_add(bmain, collection, ob);
 
-		for (ViewLayer *view_layer = scene->view_layers.first; view_layer; view_layer = view_layer->next) {
-			Base *base = BKE_view_layer_base_find(view_layer, ob);
-			if (base) {
-				ED_object_base_select(base, BA_SELECT);
-			}
+	for (ViewLayer *view_layer = scene->view_layers.first; view_layer; view_layer = view_layer->next) {
+		Base *base = BKE_view_layer_base_find(view_layer, ob);
+		if (base) {
+			ED_object_base_select(base, BA_SELECT);
 		}
+	}
 
-		DEG_relations_tag_update(bmain);
-
-		DEG_id_tag_update(&scene->id, DEG_TAG_SELECT_UPDATE);
-		WM_main_add_notifier(NC_SCENE | ND_OB_SELECT, scene);
+	DEG_relations_tag_update(bmain);
 
-		return OPERATOR_FINISHED;
-	}
+	DEG_id_tag_update(&scene->id, DEG_TAG_SELECT_UPDATE);
+	WM_main_add_notifier(NC_SCENE | ND_OB_SELECT, scene);
 
-	return OPERATOR_CANCELLED;
+	return OPERATOR_FINISHED;
 }
 
 void OUTLINER_OT_scene_drop(wmOperatorType *ot)
@@ -555,75 +495,33 @@ void OUTLINER_OT_scene_drop(wmOperatorType *ot)
 
 	/* flags */
 	ot->flag = OPTYPE_REGISTER | OPTYPE_UNDO | OPTYPE_INTERNAL;
-
-	/* properties */
-	RNA_def_string(ot->srna, "object", "Object", MAX_ID_NAME, "Object", "Target Object");
-	RNA_def_string(ot->srna, "scene", "Scene", MAX_ID_NAME, "Scene", "Target Scene");
 }
 
 /* ******************** Material Drop Operator *********************** */
 
 static bool material_drop_poll(bContext *C, wmDrag *drag, const wmEvent *event, const char **UNUSED(tooltip))
 {
-	ARegion *ar = CTX_wm_region(C);
-	SpaceOops *soops = CTX_wm_space_outliner(C);
-	float fmval[2];
-	UI_view2d_region_to_view(&ar->v2d, event->mval[0], event->mval[1], &fmval[0], &fmval[1]);
-
-	if (drag->type == WM_DRAG_ID) {
-		ID *id = drag->poin;
-		if (GS(id->name) == ID_MA) {
-			/* Ensure item under cursor is valid drop target */
-			TreeElement *te = outliner_dropzone_find(soops, fmval, true);
-			return (te && te->idcode == ID_OB && TREESTORE(te)->type == 0);
-		}
-	}
-	return 0;
+	/* Ensure item under cursor is valid drop target */
+	Material *ma = (Material *)WM_drag_ID(drag, ID_MA);
+	return (ma && (outliner_ID_drop_find(C, event, ID_OB) != NULL));
 }
 
-static void material_drop_copy(wmDrag *drag, wmDropBox *drop)
+static int material_drop_invoke(bContext *C, wmOperator *UNUSED(op), const wmEvent *event)
 {
-	ID *id = drag->poin;
-
-	RNA_string_set(drop->ptr, "material", id->name + 2);
-}
-
-static int material_drop_invoke(bContext *C, wmOperator *op, const wmEvent *event)
-{
-	Material *ma = NULL;
-	Object *ob = NULL;
 	Main *bmain = CTX_data_main(C);
-	SpaceOops *soops = CTX_wm_space_outliner(C);
-	ARegion *ar = CTX_wm_region(C);
-	TreeElement *te = NULL;
-	char mat_name[MAX_ID_NAME - 2];
-	float fmval[2];
-
-	UI_view2d_region_to_view(&ar->v2d, event->mval[0], event->mval[1], &fmval[0], &fmval[1]);
-
-	/* Find object hovered over */
-	te = outliner_dropzone_find(soops, fmval, true);
-
-	if (te) {
-		RNA_string_set(op->ptr, "object", te->name);
-		ob = (Object *)BKE_libblock_find_name(bmain, ID_OB, te->name);
+	Object *ob = (Object *)outliner_ID_drop_find(C, event, ID_OB);
+	Material *ma = (Material *)WM_drag_ID_from_event(event, ID_MA);
 
-		RNA_string_get(op->ptr, "material", mat_name);
-		ma = (Material *)BKE_libblock_find_name(bmain, ID_MA, mat_name);
-
-		if (ELEM(NULL, ob, ma)) {
-			return OPERATOR_CANCELLED;
-		}
-
-		assign_material(bmain, ob, ma, ob->totcol + 1, BKE_MAT_ASSIGN_USERPREF);
+	if (ELEM(NULL, ob, ma)) {
+		return OPERATOR_CANCELLED;
+	}
 
-		WM_event_add_notifier(C, NC_SPACE | ND_SPACE_VIEW3D, CTX_wm_view3d(C));
-		WM_event_add_notifier(C, NC_MATERIAL | ND_SHADING_LINKS, ma);
+	assign_material(bmain, ob, ma, ob->totcol + 1, BKE_MAT_ASSIGN_USERPREF);
 
-		return OPERATOR_FINISHED;
-	}
+	WM_event_add_notifier(C, NC_SPACE | ND_SPACE_VIEW3D, CTX_wm_view3d(C));
+	WM_event_add_notifier(C, NC_MATERIAL | ND_SHADING_LINKS, ma);
 
-	return OPERATOR_CANCELLED;
+	return OPERATOR_FINISHED;
 }
 
 void OUTLINER_OT_material_drop(wmOperatorType *ot)
@@ -640,80 +538,28 @@ void OUTLINER_OT_material_drop(wmOperatorType *ot)
 
 	/* flags */
 	ot->flag = OPTYPE_REGISTER | OPTYPE_UNDO | OPTYPE_INTERNAL;
-
-	/* properties */
-	RNA_def_string(ot->srna, "object", "Object", MAX_ID_NAME, "Object", "Target Object");
-	RNA_def_string(ot->srna, "material", "Material", MAX_ID_NAME, "Material", "Target Material");
 }
 
 /* ******************** Collection Drop Operator *********************** */
 
 static bool collection_drop_poll(bContext *C, wmDrag *drag, const wmEvent *event, const char **UNUSED(tooltip))
 {
-	ARegion *ar = CTX_wm_region(C);
-	SpaceOops *soops = CTX_wm_space_outliner(C);
-	float fmval[2];
-	UI_view2d_region_to_view(&ar->v2d, event->mval[0], event->mval[1], &fmval[0], &fmval[1]);
+	Object *ob = (Object *)WM_drag_ID(drag, ID_OB);
+	Collection *collection = (Collection *)WM_drag_ID(drag, ID_GR);
 
-	if (drag->type == WM_DRAG_ID) {
-		ID *id = drag->poin;
-		if (ELEM(GS(id->name), ID_OB, ID_GR)) {
-			/* Ensure item under cursor is valid drop target */
-			TreeElement *te = outliner_dropzone_find(soops, fmval, true);
-			return (te && outliner_is_collection_tree_element(te));
-		}
+	if (ob || collection) {
+		TreeElement *te = outliner_drop_find(C, event);
+		return (te && outliner_is_collection_tree_element(te));
 	}
-	return 0;
-}
-
-static void collection_drop_copy(wmDrag *drag, wmDropBox *drop)
-{
-	ID *id = drag->poin;
-	RNA_string_set(drop->ptr, "child", id->name + 2);
-}
-
-static int collection_drop_exec(bContext *UNUSED(C), wmOperator *UNUSED(op))
-{
-	/* TODO: implement */
-#if 0
-	Object *par = NULL, *ob = NULL;
-	Main *bmain = CTX_data_main(C);
-	Scene *scene = CTX_data_scene(C);
-	int partype = -1;
-	char parname[MAX_ID_NAME], childname[MAX_ID_NAME];
-
-	RNA_string_get(op->ptr, "parent", parname);
-	par = (Object *)BKE_libblock_find_name(ID_OB, parname);
-	RNA_string_get(op->ptr, "child", childname);
-	ob = (Object *)BKE_libblock_find_name(ID_OB, childname);
-
-	if (ID_IS_LINKED(ob)) {
-		BKE_report(op->reports, RPT_INFO, "Can't edit library linked object");
-		return OPERATOR_CANCELLED;
+	else {
+		return false;
 	}
-
-	ED_object_parent_set(op->reports, C, scene, ob, par, partype, false, false, NULL);
-
-	DEG_relations_tag_update(bmain);
-	WM_event_add_notifier(C, NC_OBJECT | ND_TRANSFORM, NULL);
-	WM_event_add_notifier(C, NC_OBJECT | ND_PARENT, NULL);
-#endif
-
-	return OPERATOR_FINISHED;
 }
 
-static int collection_drop_invoke(bContext *C, wmOperator *op, const wmEvent *event)
+static int collection_drop_invoke(bContext *C, wmOperator *UNUSED(op), const wmEvent *event)
 {
-	SpaceOops *soops = CTX_wm_space_outliner(C);
-	ARegion *ar = CTX_wm_region(C);
 	Main *bmain = CTX_data_main(C);
-	char childname[MAX_ID_NAME];
-	float fmval[2];
-
-	UI_view2d_region_to_view(&ar->v2d, event->mval[0], event->mval[1], &fmval[0], &fmval[1]);
-
-	/* Find object hovered over */
-	TreeElement *te = outliner_dropzone_find(soops, fmval, true);
+	TreeElement *te = outliner_drop_find(C, event);
 
 	if (!te || !outliner_is_collection_tree_element(te)) {
 		return OPERATOR_CANCELLED;
@@ -724,9 +570,11 @@ static int collection_drop_invoke(bContext *C, wmOperator *op, const wmEvent *ev
 	// TODO: don't use scene, makes no sense anymore
 	// TODO: move rather than link, change hover text
 	Scene *scene = BKE_scene_find_from_collection(bmain, collection);
-	BLI_assert(scene);
-	RNA_string_get(op->ptr, "child", childname);
-	Object *ob = (Object *)BKE_libblock_find_name(bmain, ID_OB, childname);
+	Object *ob = (Object *)WM_drag_ID_from_event(event, ID_OB);
+	if (ELEM(NULL, ob, scene, collection)) {
+		return OPERATOR_CANCELLED;
+	}
+
 	BKE_collection_object_add(bmain, collection, ob);
 
 	DEG_id_tag_update(&collection->id, DEG_TAG_COPY_ON_WRITE);
@@ -745,16 +593,10 @@ void OUTLINER_OT_collection_drop(wmOperatorType *ot)
 
 	/* api callbacks */
 	ot->invoke = collection_drop_invoke;
-	ot->exec = collection_drop_exec;
-
 	ot->poll = ED_operator_outliner_active;
 
 	/* flags */
 	ot->flag = OPTYPE_REGISTER | OPTYPE_UNDO | OPTYPE_INTERNAL;
-
-	/* properties */
-	RNA_def_string(ot->srna, "child", "Object", MAX_ID_NAME, "Child", "Child Object");
-	RNA_def_string(ot->srna, "parent", "Collection", MAX_ID_NAME, "Parent", "Parent Collection");
 }
 
 /* ********************* Outliner Drag Operator ******************** */
@@ -1107,9 +949,9 @@ void outliner_dropboxes(void)
 {
 	ListBase *lb = WM_dropboxmap_find("Outliner", SPACE_OUTLINER, RGN_TYPE_WINDOW);
 
-	WM_dropbox_add(lb, "OUTLINER_OT_parent_drop", parent_drop_poll, parent_drop_copy);
-	WM_dropbox_add(lb, "OUTLINER_OT_parent_clear", parent_clear_poll, parent_clear_copy);
-	WM_dropbox_add(lb, "OUTLINER_OT_scene_drop", scene_drop_poll, scene_drop_copy);
-	WM_dropbox_add(lb, "OUTLINER_OT_material_drop", material_drop_poll, material_drop_copy);
-	WM_dropbox_add(lb, "OUTLINER_OT_collection_drop", collection_drop_poll, collection_drop_copy);
+	WM_dropbox_add(lb, "OUTLINER_OT_parent_drop", parent_drop_poll, NULL);
+	WM_dropbox_add(lb, "OUTLINER_OT_parent_clear", parent_clear_poll, NULL);
+	WM_dropbox_add(lb, "OUTLINER_OT_scene_drop", scene_drop_poll, NULL);
+	WM_dropbox_add(lb, "OUTLINER_OT_material_drop", material_drop_poll, NULL);
+	WM_dropbox_add(lb, "OUTLINER_OT_collection_drop", collection_drop_poll, NULL);
 }
diff --git a/source/blender/editors/space_text/space_text.c b/source/blender/editors/space_text/space_text.c
index 53272ee9ed9..469e1b84c29 100644
--- a/source/blender/editors/space_text/space_text.c
+++ b/source/blender/editors/space_text/space_text.c
@@ -493,10 +493,7 @@ static void text_drop_copy(wmDrag *drag, wmDropBox *drop)
 
 static bool text_drop_paste_poll(bContext *UNUSED(C), wmDrag *drag, const wmEvent *UNUSED(event), const char **UNUSED(tooltip))
 {
-	if (drag->type == WM_DRAG_ID)
-		return true;
-
-	return false;
+	return (drag->type == WM_DRAG_ID);
 }
 
 static void text_drop_paste(wmDrag *drag, wmDropBox *drop)
diff --git a/source/blender/editors/space_view3d/space_view3d.c b/source/blender/editors/space_view3d/space_view3d.c
index 62adca6af6b..68ea59859da 100644
--- a/source/blender/editors/space_view3d/space_view3d.c
+++ b/source/blender/editors/space_view3d/space_view3d.c
@@ -556,46 +556,27 @@ static void view3d_main_region_exit(wmWindowManager *wm, ARegion *ar)
 
 static bool view3d_ob_drop_poll(bContext *UNUSED(C), wmDrag *drag, const wmEvent *UNUSED(event), const char **UNUSED(tooltip))
 {
-	if (drag->type == WM_DRAG_ID) {
-		ID *id = drag->poin;
-		if (GS(id->name) == ID_OB)
-			return 1;
-	}
-	return 0;
+	return WM_drag_ID(drag, ID_OB) != NULL;
 }
 
 static bool view3d_collection_drop_poll(bContext *UNUSED(C), wmDrag *drag, const wmEvent *UNUSED(event), const char **UNUSED(tooltip))
 {
-	if (drag->type == WM_DRAG_ID) {
-		ID *id = drag->poin;
-		if (GS(id->name) == ID_GR)
-			return 1;
-	}
-	return 0;
+	return WM_drag_ID(drag, ID_GR) != NULL;
 }
 
 static bool view3d_mat_drop_poll(bContext *UNUSED(C), wmDrag *drag, const wmEvent *UNUSED(event), const char **UNUSED(tooltip))
 {
-	if (drag->type == WM_DRAG_ID) {
-		ID *id = drag->poin;
-		if (GS(id->name) == ID_MA)
-			return 1;
-	}
-	return 0;
+	return WM_drag_ID(drag, ID_MA) != NULL;
 }
 
 static bool view3d_ima_drop_poll(bContext *UNUSED(C), wmDrag *drag, const wmEvent *UNUSED(event), const char **UNUSED(tooltip))
 {
-	if (drag->type == WM_DRAG_ID) {
-		ID *id = drag->poin;
-		if (GS(id->name) == ID_IM)
-			return 1;
+	if (drag->type == WM_DRAG_PATH) {
+		return (ELEM(drag->icon, 0, ICON_FILE_IMAGE, ICON_FILE_MOVIE));   /* rule might not work? */
 	}
-	else if (drag->type == WM_DRAG_PATH) {
-		if (ELEM(drag->icon, 0, ICON_FILE_IMAGE, ICON_FILE_MOVIE))   /* rule might not work? */
-			return 1;
+	else {
+		return WM_drag_ID(drag, ID_IM) != NULL;
 	}
-	return 0;
 }
 
 static bool view3d_ima_bg_is_camera_view(bContext *C)
diff --git a/source/blender/windowmanager/WM_api.h b/source/blender/windowmanager/WM_api.h
index 3521c4d1bd5..d175b11fe5c 100644
--- a/source/blender/windowmanager/WM_api.h
+++ b/source/blender/windowmanager/WM_api.h
@@ -484,6 +484,9 @@ void				WM_event_drag_image(struct wmDrag *, struct ImBuf *, float scale, int sx
 void                WM_drag_free(struct wmDrag *drag);
 void                WM_drag_free_list(struct ListBase *lb);
 
+struct ID          *WM_drag_ID(const struct wmDrag *drag, short idcode);
+struct ID          *WM_drag_ID_from_event(const struct wmEvent *event, short idcode);
+
 struct wmDropBox	*WM_dropbox_add(
         ListBase *lb, const char *idname,
         bool (*poll)(struct bContext *, struct wmDrag *, const struct wmEvent *event, const char **),
diff --git a/source/blender/windowmanager/intern/wm_dragdrop.c b/source/blender/windowmanager/intern/wm_dragdrop.c
index 0ae51cc922b..6b9a7fb5430 100644
--- a/source/blender/windowmanager/intern/wm_dragdrop.c
+++ b/source/blender/windowmanager/intern/wm_dragdrop.c
@@ -189,6 +189,27 @@ void WM_drag_free_list(struct ListBase *lb)
 	}
 }
 
+
+ID *WM_drag_ID(const wmDrag *drag, short idcode)
+{
+	if (drag->type != WM_DRAG_ID) {
+		return NULL;
+	}
+
+	ID *id = drag->poin;
+	return (idcode == 0 || GS(id->name) == idcode) ? id : NULL;
+}
+
+ID *WM_drag_ID_from_event(const wmEvent *event, short idcode)
+{
+	if (event->custom != EVT_DATA_DRAGDROP) {
+		return NULL;
+	}
+
+	ListBase *lb = event->customdata;
+	return WM_drag_ID(lb->first, idcode);
+}
+
 static const char *dropbox_active(bContext *C, ListBase *handlers, wmDrag *drag, const wmEvent *event)
 {
 	wmEventHandler *handler = handlers->first;
diff --git a/source/blender/windowmanager/intern/wm_event_system.c b/source/blender/windowmanager/intern/wm_event_system.c
index 5d343c5e0fe..0581d41ea04 100644
--- a/source/blender/windowmanager/intern/wm_event_system.c
+++ b/source/blender/windowmanager/intern/wm_event_system.c
@@ -98,7 +98,7 @@ static void wm_notifier_clear(wmNotifier *note);
 static void update_tablet_data(wmWindow *win, wmEvent *event);
 
 static int wm_operator_call_internal(bContext *C, wmOperatorType *ot, PointerRNA *properties, ReportList *reports,
-                                     const short context, const bool poll_only);
+                                     const short context, const bool poll_only, wmEvent *event);
 
 /* ************ event management ************** */
 
@@ -638,7 +638,7 @@ bool WM_operator_poll(bContext *C, wmOperatorType *ot)
 /* sets up the new context and calls 'wm_operator_invoke()' with poll_only */
 bool WM_operator_poll_context(bContext *C, wmOperatorType *ot, short context)
 {
-	return wm_operator_call_internal(C, ot, NULL, NULL, context, true);
+	return wm_operator_call_internal(C, ot, NULL, NULL, context, true, NULL);
 }
 
 bool WM_operator_check_ui_empty(wmOperatorType *ot)
@@ -1431,10 +1431,8 @@ static int wm_operator_invoke(
  */
 static int wm_operator_call_internal(
         bContext *C, wmOperatorType *ot, PointerRNA *properties, ReportList *reports,
-        const short context, const bool poll_only)
+        const short context, const bool poll_only, wmEvent *event)
 {
-	wmEvent *event;
-
 	int retval;
 
 	CTX_wm_operator_poll_msg_set(C, NULL);
@@ -1443,27 +1441,29 @@ static int wm_operator_call_internal(
 	if (ot) {
 		wmWindow *window = CTX_wm_window(C);
 
-		switch (context) {
-			case WM_OP_INVOKE_DEFAULT:
-			case WM_OP_INVOKE_REGION_WIN:
-			case WM_OP_INVOKE_REGION_PREVIEW:
-			case WM_OP_INVOKE_REGION_CHANNELS:
-			case WM_OP_INVOKE_AREA:
-			case WM_OP_INVOKE_SCREEN:
-				/* window is needed for invoke, cancel operator */
-				if (window == NULL) {
-					if (poll_only) {
-						CTX_wm_operator_poll_msg_set(C, "Missing 'window' in context");
+		if (event == NULL) {
+			switch (context) {
+				case WM_OP_INVOKE_DEFAULT:
+				case WM_OP_INVOKE_REGION_WIN:
+				case WM_OP_INVOKE_REGION_PREVIEW:
+				case WM_OP_INVOKE_REGION_CHANNELS:
+				case WM_OP_INVOKE_AREA:
+				case WM_OP_INVOKE_SCREEN:
+					/* window is needed for invoke, cancel operator */
+					if (window == NULL) {
+						if (poll_only) {
+							CTX_wm_operator_poll_msg_set(C, "Missing 'window' in context");
+						}
+						return 0;
 					}
-					return 0;
-				}
-				else {
-					event = window->eventstate;
-				}
-				break;
-			default:
-				event = NULL;
-				break;
+					else {
+						event = window->eventstate;
+					}
+					break;
+				default:
+					event = NULL;
+					break;
+			}
 		}
 
 		switch (context) {
@@ -1561,7 +1561,7 @@ static int wm_operator_call_internal(
 int WM_operator_name_call_ptr(bContext *C, wmOperatorType *ot, short context, PointerRNA *properties)
 {
 	BLI_assert(ot == WM_operatortype_find(ot->idname, true));
-	return wm_operator_call_internal(C, ot, properties, NULL, context, false);
+	return wm_operator_call_internal(C, ot, properties, NULL, context, false, NULL);
 }
 int WM_operator_name_call(bContext *C, const char *opstring, short context, PointerRNA *properties)
 {
@@ -1627,7 +1627,7 @@ int WM_operator_call_py(
 	wmWindowManager *wm = CTX_wm_manager(C);
 	if (!is_undo && wm) wm->op_undo_depth++;
 
-	retval = wm_operator_call_internal(C, ot, properties, reports, context, false);
+	retval = wm_operator_call_internal(C, ot, properties, reports, context, false, NULL);
 
 	if (!is_undo && wm && (wm == CTX_wm_manager(C))) wm->op_undo_depth--;
 
@@ -2370,17 +2370,26 @@ static int wm_handlers_do_intern(bContext *C, wmEvent *event, ListBase *handlers
 							for (drag = lb->first; drag; drag = drag->next) {
 								const char *tooltip = NULL;
 								if (drop->poll(C, drag, event, &tooltip)) {
-									drop->copy(drag, drop);
+									/* Optionally copy drag information to operator properties. */
+									if (drop->copy) {
+										drop->copy(drag, drop);
+									}
 
-									/* free the drags before calling operator */
+									/* Pass single matched wmDrag onto the operator. */
+									BLI_remlink(lb, drag);
+									ListBase single_lb = {drag, drag};
+									event->customdata = &single_lb;
+
+									wm_operator_call_internal(C, drop->ot, drop->ptr, NULL, drop->opcontext, false, event);
+									action |= WM_HANDLER_BREAK;
+
+									/* free the drags */
 									WM_drag_free_list(lb);
+									WM_drag_free_list(&single_lb);
 
 									event->customdata = NULL;
 									event->custom = 0;
 
-									WM_operator_name_call_ptr(C, drop->ot, drop->opcontext, drop->ptr);
-									action |= WM_HANDLER_BREAK;
-
 									/* XXX fileread case */
 									if (CTX_wm_window(C) == NULL)
 										return action;