Tool System: per space/mode tool support

This patch adds support for:

- Per space-type tools (3D view and edit).
- Per mode tools (object, edit, weight-paint .. etc).

The top-bar shows the last activated tools options, this is a design
issue with using a global topbar to show per-space settings.

See D3395

26 files changed, 599 insertions, 165 deletions

diff --git a/source/blender/blenkernel/intern/workspace.c b/source/blender/blenkernel/intern/workspace.c
index 38378f66584..fd316cb9d82 100644
--- a/source/blender/blenkernel/intern/workspace.c
+++ b/source/blender/blenkernel/intern/workspace.c
@@ -171,6 +171,14 @@ void BKE_workspace_free(WorkSpace *workspace)
 
 	BLI_freelistN(&workspace->owner_ids);
 	BLI_freelistN(&workspace->layouts);
+
+	for (bToolRef *tref = workspace->tools.first, *tref_next; tref; tref = tref_next) {
+		tref_next = tref->next;
+		if (tref->runtime) {
+			MEM_freeN(tref->runtime);
+		}
+	}
+	BLI_freelistN(&workspace->tools);
 }
 
 /**
diff --git a/source/blender/blenloader/intern/readfile.c b/source/blender/blenloader/intern/readfile.c
index 9618ae432f1..42984cfefaa 100644
--- a/source/blender/blenloader/intern/readfile.c
+++ b/source/blender/blenloader/intern/readfile.c
@@ -2911,6 +2911,7 @@ static void direct_link_workspace(FileData *fd, WorkSpace *workspace, const Main
 	link_list(fd, &workspace->hook_layout_relations);
 	link_list(fd, &workspace->scene_viewlayer_relations);
 	link_list(fd, &workspace->owner_ids);
+	link_list(fd, &workspace->tools);
 
 	for (WorkSpaceDataRelation *relation = workspace->hook_layout_relations.first;
 	     relation;
@@ -2936,6 +2937,10 @@ static void direct_link_workspace(FileData *fd, WorkSpace *workspace, const Main
 			}
 		}
 	}
+
+	for (bToolRef *tref = workspace->tools.first; tref; tref = tref->next) {
+		tref->runtime = NULL;
+	}
 }
 
 static void lib_link_workspace_instance_hook(FileData *fd, WorkSpaceInstanceHook *hook, ID *id)
diff --git a/source/blender/blenloader/intern/writefile.c b/source/blender/blenloader/intern/writefile.c
index bb136cb937d..507fe2e082c 100644
--- a/source/blender/blenloader/intern/writefile.c
+++ b/source/blender/blenloader/intern/writefile.c
@@ -3598,6 +3598,7 @@ static void write_workspace(WriteData *wd, WorkSpace *workspace)
 	writelist(wd, DATA, WorkSpaceDataRelation, &workspace->hook_layout_relations);
 	writelist(wd, DATA, WorkSpaceDataRelation, &workspace->scene_viewlayer_relations);
 	writelist(wd, DATA, wmOwnerID, &workspace->owner_ids);
+	writelist(wd, DATA, bToolRef, &workspace->tools);
 }
 
 /* Keep it last of write_foodata functions. */
diff --git a/source/blender/editors/mesh/editmesh_extrude.c b/source/blender/editors/mesh/editmesh_extrude.c
index 2e3d0a9c675..67596ef5c8a 100644
--- a/source/blender/editors/mesh/editmesh_extrude.c
+++ b/source/blender/editors/mesh/editmesh_extrude.c
@@ -420,7 +420,10 @@ static void manipulator_mesh_extrude_orientation_matrix_set(
 static bool manipulator_mesh_extrude_poll(const bContext *C, wmManipulatorGroupType *wgt)
 {
 	WorkSpace *workspace = CTX_wm_workspace(C);
-	if (!STREQ(workspace->tool.manipulator_group, "MESH_WGT_extrude") ||
+	const bToolKey tkey = { .space_type = SPACE_VIEW3D, .mode = OB_MODE_EDIT};
+	bToolRef_Runtime *tref_rt = WM_toolsystem_runtime_find(workspace, &tkey);
+	if ((tref_rt == NULL) ||
+	    !STREQ(wgt->idname, tref_rt->manipulator_group) ||
 	    !ED_operator_editmesh_view3d((bContext *)C))
 	{
 		WM_manipulator_group_type_unlink_delayed_ptr(wgt);
diff --git a/source/blender/editors/object/object_edit.c b/source/blender/editors/object/object_edit.c
index e87a24b3af0..b9a7da02611 100644
--- a/source/blender/editors/object/object_edit.c
+++ b/source/blender/editors/object/object_edit.c
@@ -481,6 +481,8 @@ static int editmode_toggle_exec(bContext *C, wmOperator *op)
 
 	WM_msg_publish_rna_prop(mbus, &obact->id, obact, Object, mode);
 
+	WM_toolsystem_update_from_context_view3d(C);
+
 	return OPERATOR_FINISHED;
 }
 
@@ -579,6 +581,8 @@ static int posemode_exec(bContext *C, wmOperator *op)
 
 	WM_msg_publish_rna_prop(mbus, &obact->id, obact, Object, mode);
 
+	WM_toolsystem_update_from_context_view3d(C);
+
 	return OPERATOR_FINISHED;
 }
 
diff --git a/source/blender/editors/physics/particle_edit.c b/source/blender/editors/physics/particle_edit.c
index e0427b4797c..6197457293f 100644
--- a/source/blender/editors/physics/particle_edit.c
+++ b/source/blender/editors/physics/particle_edit.c
@@ -4527,6 +4527,8 @@ static int particle_edit_toggle_exec(bContext *C, wmOperator *op)
 
 	WM_msg_publish_rna_prop(mbus, &ob->id, ob, Object, mode);
 
+	WM_toolsystem_update_from_context_view3d(C);
+
 	return OPERATOR_FINISHED;
 }
 
diff --git a/source/blender/editors/screen/workspace_edit.c b/source/blender/editors/screen/workspace_edit.c
index bd4381f4099..fe52e945399 100644
--- a/source/blender/editors/screen/workspace_edit.c
+++ b/source/blender/editors/screen/workspace_edit.c
@@ -201,8 +201,8 @@ bool ED_workspace_change(
 		BLI_assert(BKE_workspace_view_layer_get(workspace_new, CTX_data_scene(C)) != NULL);
 		BLI_assert(CTX_wm_workspace(C) == workspace_new);
 
-		WM_toolsystem_unlink(C, workspace_old);
-		WM_toolsystem_link(C, workspace_new);
+		WM_toolsystem_unlink_all(C, workspace_old);
+		WM_toolsystem_link_all(C, workspace_new);
 
 		return true;
 	}
@@ -224,7 +224,7 @@ WorkSpace *ED_workspace_duplicate(
 	        bmain, workspace_old->id.name + 2, scene,
 	        BKE_workspace_view_layer_get(workspace_old, scene));
 
-	workspace_new->tool = workspace_old->tool;
+	/* TODO(campbell): tools */
 
 	for (WorkSpaceLayout *layout_old = layouts_old->first; layout_old; layout_old = layout_old->next) {
 		WorkSpaceLayout *layout_new = ED_workspace_layout_duplicate(workspace_new, layout_old, win);
diff --git a/source/blender/editors/sculpt_paint/paint_image.c b/source/blender/editors/sculpt_paint/paint_image.c
index cbf755d26b5..6a32fdecfad 100644
--- a/source/blender/editors/sculpt_paint/paint_image.c
+++ b/source/blender/editors/sculpt_paint/paint_image.c
@@ -1136,6 +1136,8 @@ static int texture_paint_toggle_exec(bContext *C, wmOperator *op)
 
 	WM_msg_publish_rna_prop(mbus, &ob->id, ob, Object, mode);
 
+	WM_toolsystem_update_from_context_view3d(C);
+
 	return OPERATOR_FINISHED;
 }
 
diff --git a/source/blender/editors/sculpt_paint/paint_vertex.c b/source/blender/editors/sculpt_paint/paint_vertex.c
index 196505c9542..3c3df2067ab 100644
--- a/source/blender/editors/sculpt_paint/paint_vertex.c
+++ b/source/blender/editors/sculpt_paint/paint_vertex.c
@@ -1252,6 +1252,8 @@ static int wpaint_mode_toggle_exec(bContext *C, wmOperator *op)
 
 	WM_msg_publish_rna_prop(mbus, &ob->id, ob, Object, mode);
 
+	WM_toolsystem_update_from_context_view3d(C);
+
 	return OPERATOR_FINISHED;
 }
 
@@ -2386,6 +2388,8 @@ static int vpaint_mode_toggle_exec(bContext *C, wmOperator *op)
 
 	WM_msg_publish_rna_prop(mbus, &ob->id, ob, Object, mode);
 
+	WM_toolsystem_update_from_context_view3d(C);
+
 	return OPERATOR_FINISHED;
 }
 
diff --git a/source/blender/editors/sculpt_paint/sculpt.c b/source/blender/editors/sculpt_paint/sculpt.c
index 048555d3fcc..709d6d4c690 100644
--- a/source/blender/editors/sculpt_paint/sculpt.c
+++ b/source/blender/editors/sculpt_paint/sculpt.c
@@ -5820,6 +5820,8 @@ static int sculpt_mode_toggle_exec(bContext *C, wmOperator *op)
 
 	WM_msg_publish_rna_prop(mbus, &ob->id, ob, Object, mode);
 
+	WM_toolsystem_update_from_context_view3d(C);
+
 	return OPERATOR_FINISHED;
 }
 
diff --git a/source/blender/editors/space_topbar/space_topbar.c b/source/blender/editors/space_topbar/space_topbar.c
index 8cf27d86cfe..4342fa87f89 100644
--- a/source/blender/editors/space_topbar/space_topbar.c
+++ b/source/blender/editors/space_topbar/space_topbar.c
@@ -201,9 +201,10 @@ static void topbar_header_region_message_subscribe(
 		.user_data = ar,
 		.notify = ED_region_do_msg_notify_tag_redraw,
 	};
+
 	WM_msg_subscribe_rna_prop(
 	        mbus, &workspace->id, workspace,
-	        WorkSpace, tool_keymap, &msg_sub_value_region_tag_redraw);
+	        WorkSpace, tools, &msg_sub_value_region_tag_redraw);
 }
 
 static void recent_files_menu_draw(const bContext *UNUSED(C), Menu *menu)
diff --git a/source/blender/editors/space_view3d/space_view3d.c b/source/blender/editors/space_view3d/space_view3d.c
index fa147ff1226..de2ef45247b 100644
--- a/source/blender/editors/space_view3d/space_view3d.c
+++ b/source/blender/editors/space_view3d/space_view3d.c
@@ -1017,8 +1017,8 @@ static void view3d_main_region_listener(
 
 static void view3d_main_region_message_subscribe(
         const struct bContext *C,
-        struct WorkSpace *workspace, struct Scene *UNUSED(scene),
-        struct bScreen *UNUSED(screen), struct ScrArea *UNUSED(sa), struct ARegion *ar,
+        struct WorkSpace *UNUSED(workspace), struct Scene *UNUSED(scene),
+        struct bScreen *UNUSED(screen), struct ScrArea *sa, struct ARegion *ar,
         struct wmMsgBus *mbus)
 {
 	/* Developer note: there are many properties that impact 3D view drawing,
@@ -1091,10 +1091,10 @@ static void view3d_main_region_message_subscribe(
 		}
 	}
 
-	if (workspace->tool.spacetype == SPACE_VIEW3D) {
+	{
 		wmMsgSubscribeValue msg_sub_value_region_tag_refresh = {
 			.owner = ar,
-			.user_data = ar,
+			.user_data = sa,
 			.notify = WM_toolsystem_do_msg_notify_tag_refresh,
 		};
 		WM_msg_subscribe_rna_anon_prop(
diff --git a/source/blender/editors/space_view3d/view3d_manipulator_ruler.c b/source/blender/editors/space_view3d/view3d_manipulator_ruler.c
index 9f69a33861d..d46673b4817 100644
--- a/source/blender/editors/space_view3d/view3d_manipulator_ruler.c
+++ b/source/blender/editors/space_view3d/view3d_manipulator_ruler.c
@@ -982,8 +982,10 @@ void VIEW3D_WT_ruler_item(wmManipulatorType *wt)
 
 static bool WIDGETGROUP_ruler_poll(const bContext *C, wmManipulatorGroupType *wgt)
 {
-	WorkSpace *workspace = CTX_wm_workspace(C);
-	if (!STREQ(wgt->idname, workspace->tool.manipulator_group)) {
+	bToolRef_Runtime *tref_rt = WM_toolsystem_runtime_from_context((bContext *)C);
+	if ((tref_rt == NULL) ||
+	    !STREQ(wgt->idname, tref_rt->manipulator_group))
+	{
 		WM_manipulator_group_type_unlink_delayed_ptr(wgt);
 		return false;
 	}
@@ -1030,8 +1032,9 @@ void VIEW3D_WGT_ruler(wmManipulatorGroupType *wgt)
 
 static int view3d_ruler_poll(bContext *C)
 {
-	WorkSpace *workspace = CTX_wm_workspace(C);
-	if (!STREQ(view3d_wgt_ruler_id, workspace->tool.manipulator_group) ||
+	bToolRef_Runtime *tref_rt = WM_toolsystem_runtime_from_context((bContext *)C);
+	if ((tref_rt == NULL) ||
+	    !STREQ(view3d_wgt_ruler_id, tref_rt->manipulator_group) ||
 	    CTX_wm_region_view3d(C) == NULL)
 	{
 		return false;
diff --git a/source/blender/editors/transform/transform_manipulator_3d.c b/source/blender/editors/transform/transform_manipulator_3d.c
index 8257ad595d7..c24291953c8 100644
--- a/source/blender/editors/transform/transform_manipulator_3d.c
+++ b/source/blender/editors/transform/transform_manipulator_3d.c
@@ -1283,8 +1283,14 @@ static void WIDGETGROUP_manipulator_setup(const bContext *C, wmManipulatorGroup
 		/* TODO: support mixing modes again? - it's supported but tool system makes it unobvious. */
 		man->twtype = 0;
 		WorkSpace *workspace = CTX_wm_workspace(C);
+		Scene *scene = CTX_data_scene(C);
 		ScrArea *sa = CTX_wm_area(C);
-		wmKeyMap *km = WM_keymap_find_all(C, workspace->tool.keymap, sa->spacetype, RGN_TYPE_WINDOW);
+		const bToolKey tkey = {
+			.space_type = sa->spacetype,
+			.mode = WM_toolsystem_mode_from_spacetype(workspace, scene, NULL, sa->spacetype),
+		};
+		bToolRef_Runtime *tref_rt = WM_toolsystem_runtime_find(workspace, &tkey);
+		wmKeyMap *km = WM_keymap_find_all(C, tref_rt->keymap, sa->spacetype, RGN_TYPE_WINDOW);
 		/* Weak, check first event */
 		wmKeyMapItem *kmi = km ? km->items.first : NULL;
 
@@ -1552,8 +1558,10 @@ static bool WIDGETGROUP_manipulator_poll(const struct bContext *C, struct wmMani
 		return false;
 	}
 
-	WorkSpace *workspace = CTX_wm_workspace(C);
-	if (!STREQ(workspace->tool.manipulator_group, "TRANSFORM_WGT_manipulator")) {
+	bToolRef_Runtime *tref_rt = WM_toolsystem_runtime_from_context((bContext *)C);
+	if ((tref_rt == NULL) ||
+	    !STREQ(wgt->idname, tref_rt->manipulator_group))
+	{
 		WM_manipulator_group_type_unlink_delayed_ptr(wgt);
 		return false;
 	}
@@ -1596,8 +1604,8 @@ static bool WIDGETGROUP_xform_cage_poll(const bContext *C, wmManipulatorGroupTyp
 		return false;
 	}
 
-	WorkSpace *workspace = CTX_wm_workspace(C);
-	if (!STREQ(wgt->idname, workspace->tool.manipulator_group)) {
+	bToolRef_Runtime *tref_rt = WM_toolsystem_runtime_from_context((bContext *)C);
+	if (!STREQ(wgt->idname, tref_rt->manipulator_group)) {
 		WM_manipulator_group_type_unlink_delayed_ptr(wgt);
 		return false;
 	}
diff --git a/source/blender/makesdna/DNA_workspace_types.h b/source/blender/makesdna/DNA_workspace_types.h
index 4cc3929b4ea..693e4f672d2 100644
--- a/source/blender/makesdna/DNA_workspace_types.h
+++ b/source/blender/makesdna/DNA_workspace_types.h
@@ -53,16 +53,35 @@
 /* Currently testing, allow to disable. */
 #define USE_WORKSPACE_TOOL
 
-typedef struct bToolDef {
+#
+#
+typedef struct bToolRef_Runtime {
 	/* One of these must be defined. */
 	char keymap[64];
 	char manipulator_group[64];
 	char data_block[64];
-
-	int  spacetype;
 	/* index when a tool is a member of a group */
-	int  index;
-} bToolDef;
+	int index;
+} bToolRef_Runtime;
+
+
+/* Stored per mode. */
+typedef struct bToolRef {
+	struct bToolRef *next, *prev;
+	char idname[64];
+
+	/** bToolKey (spacetype, mode), used in 'WM_api.h' */
+	int space_type;
+	/**
+	 * Value depends ont the 'space_type', object mode for 3D view, image editor has own mode too.
+	 * RNA needs to handle using item function.
+	 */
+	int mode;
+
+	/** Variables needed to operate the tool. */
+	bToolRef_Runtime *runtime;
+} bToolRef;
+
 
 /**
  * \brief Wrapper for bScreen.
@@ -97,13 +116,22 @@ typedef struct WorkSpace {
 	/* Feature tagging (use for addons) */
 	ListBase owner_ids DNA_PRIVATE_WORKSPACE_READ_WRITE; /* wmOwnerID */
 
-	int pad;
-	int flags DNA_PRIVATE_WORKSPACE; /* enum eWorkSpaceFlags */
+	struct ViewLayer *view_layer DNA_DEPRECATED;
 
 	/* should be: '#ifdef USE_WORKSPACE_TOOL'. */
-	bToolDef tool;
 
-	struct ViewLayer *view_layer DNA_DEPRECATED;
+	/** List of #bToolRef */
+	ListBase tools;
+
+	/**
+	 * BAD DESIGN WARNING:
+	 * This is a workaround for the topbar not knowing which tools spac */
+	char tools_space_type;
+	/** Type is different for each space-type. */
+	char tools_mode;
+
+	char _pad[2];
+	int flags DNA_PRIVATE_WORKSPACE; /* enum eWorkSpaceFlags */
 } WorkSpace;
 
 /* internal struct, but exported for read/write */
diff --git a/source/blender/makesrna/RNA_enum_types.h b/source/blender/makesrna/RNA_enum_types.h
index d5b2493078c..447dc4ce289 100644
--- a/source/blender/makesrna/RNA_enum_types.h
+++ b/source/blender/makesrna/RNA_enum_types.h
@@ -56,6 +56,7 @@ extern const EnumPropertyItem rna_enum_curve_fit_method_items[];
 extern const EnumPropertyItem rna_enum_mesh_select_mode_items[];
 extern const EnumPropertyItem rna_enum_mesh_delimit_mode_items[];
 extern const EnumPropertyItem rna_enum_space_type_items[];
+extern const EnumPropertyItem rna_enum_space_image_mode_items[];
 extern const EnumPropertyItem rna_enum_region_type_items[];
 extern const EnumPropertyItem rna_enum_object_modifier_type_items[];
 extern const EnumPropertyItem rna_enum_constraint_type_items[];
diff --git a/source/blender/makesrna/intern/CMakeLists.txt b/source/blender/makesrna/intern/CMakeLists.txt
index 7bd5ad2b959..c62e8ed4da8 100644
--- a/source/blender/makesrna/intern/CMakeLists.txt
+++ b/source/blender/makesrna/intern/CMakeLists.txt
@@ -122,6 +122,7 @@ set(APISRC
 	rna_vfont_api.c
 	rna_wm_api.c
 	rna_wm_manipulator_api.c
+	rna_workspace_api.c
 )
 
 string(REGEX REPLACE "rna_([a-zA-Z0-9_-]*).c" "${CMAKE_CURRENT_BINARY_DIR}/rna_\\1_gen.c" GENSRC "${DEFSRC}")
diff --git a/source/blender/makesrna/intern/makesrna.c b/source/blender/makesrna/intern/makesrna.c
index 0b2efe27059..4daf8b6a965 100644
--- a/source/blender/makesrna/intern/makesrna.c
+++ b/source/blender/makesrna/intern/makesrna.c
@@ -2831,6 +2831,10 @@ static void rna_generate_struct_prototypes(FILE *f)
 					if (dp->prop->type == PROP_POINTER) {
 						int a, found = 0;
 						const char *struct_name = rna_parameter_type_name(dp->prop);
+						if (struct_name == NULL) {
+							printf("No struct found for property '%s'\n", dp->prop->identifier);
+							exit(1);
+						}
 
 						for (a = 0; a < all_structures; a++) {
 							if (STREQ(struct_name, structures[a])) {
@@ -3404,7 +3408,7 @@ static RNAProcessItem PROCESS_ITEMS[] = {
 	{"rna_vfont.c", "rna_vfont_api.c", RNA_def_vfont},
 	{"rna_wm.c", "rna_wm_api.c", RNA_def_wm},
 	{"rna_wm_manipulator.c", "rna_wm_manipulator_api.c", RNA_def_wm_manipulator},
-	{"rna_workspace.c", NULL, RNA_def_workspace},
+	{"rna_workspace.c", "rna_workspace_api.c", RNA_def_workspace},
 	{"rna_world.c", NULL, RNA_def_world},
 	{"rna_movieclip.c", NULL, RNA_def_movieclip},
 	{"rna_tracking.c", NULL, RNA_def_tracking},
diff --git a/source/blender/makesrna/intern/rna_internal.h b/source/blender/makesrna/intern/rna_internal.h
index 11ad39a2dd1..ce16cb69bbd 100644
--- a/source/blender/makesrna/intern/rna_internal.h
+++ b/source/blender/makesrna/intern/rna_internal.h
@@ -342,6 +342,8 @@ void RNA_api_sequences(BlenderRNA *brna, PropertyRNA *cprop);
 void RNA_api_sequence_elements(BlenderRNA *brna, PropertyRNA *cprop);
 void RNA_api_sound(struct StructRNA *srna);
 void RNA_api_vfont(struct StructRNA *srna);
+void RNA_api_workspace(struct StructRNA *srna);
+void RNA_api_workspace_tool(struct StructRNA *srna);
 
 /* main collection functions */
 void RNA_def_main_cameras(BlenderRNA *brna, PropertyRNA *cprop);
diff --git a/source/blender/makesrna/intern/rna_space.c b/source/blender/makesrna/intern/rna_space.c
index 12bb4dd0617..3ce799dfb88 100644
--- a/source/blender/makesrna/intern/rna_space.c
+++ b/source/blender/makesrna/intern/rna_space.c
@@ -103,6 +103,15 @@ const EnumPropertyItem rna_enum_space_type_items[] = {
 	{0, NULL, 0, NULL, NULL}
 };
 
+
+const EnumPropertyItem rna_enum_space_image_mode_items[] = {
+	{SI_MODE_VIEW, "VIEW", ICON_FILE_IMAGE, "View", "View the image and UV edit in mesh editmode"},
+	{SI_MODE_PAINT, "PAINT", ICON_TPAINT_HLT, "Paint", "2D image painting mode"},
+	{SI_MODE_MASK, "MASK", ICON_MOD_MASK, "Mask", "Mask editing"},
+	{0, NULL, 0, NULL, NULL}
+};
+
+
 #define V3D_S3D_CAMERA_LEFT        {STEREO_LEFT_ID, "LEFT", ICON_RESTRICT_RENDER_OFF, "Left", ""},
 #define V3D_S3D_CAMERA_RIGHT       {STEREO_RIGHT_ID, "RIGHT", ICON_RESTRICT_RENDER_OFF, "Right", ""},
 #define V3D_S3D_CAMERA_S3D         {STEREO_3D_ID, "S3D", ICON_CAMERA_STEREO, "3D", ""},
@@ -2950,13 +2959,6 @@ static void rna_def_space_buttons(BlenderRNA *brna)
 
 static void rna_def_space_image(BlenderRNA *brna)
 {
-	static const EnumPropertyItem image_space_mode_items[] = {
-		{SI_MODE_VIEW, "VIEW", ICON_FILE_IMAGE, "View", "View the image and UV edit in mesh editmode"},
-		{SI_MODE_PAINT, "PAINT", ICON_TPAINT_HLT, "Paint", "2D image painting mode"},
-		{SI_MODE_MASK, "MASK", ICON_MOD_MASK, "Mask", "Mask editing"},
-		{0, NULL, 0, NULL, NULL}
-	};
-
 	StructRNA *srna;
 	PropertyRNA *prop;
 
@@ -3037,7 +3039,7 @@ static void rna_def_space_image(BlenderRNA *brna)
 	/* mode */
 	prop = RNA_def_property(srna, "mode", PROP_ENUM, PROP_NONE);
 	RNA_def_property_enum_sdna(prop, NULL, "mode");
-	RNA_def_property_enum_items(prop, image_space_mode_items);
+	RNA_def_property_enum_items(prop, rna_enum_space_image_mode_items);
 	RNA_def_property_ui_text(prop, "Mode", "Editing context being displayed");
 	RNA_def_property_update(prop, NC_SPACE | ND_SPACE_IMAGE, "rna_SpaceImageEditor_mode_update");
 
diff --git a/source/blender/makesrna/intern/rna_workspace.c b/source/blender/makesrna/intern/rna_workspace.c
index b82ca145f5f..485cb298dae 100644
--- a/source/blender/makesrna/intern/rna_workspace.c
+++ b/source/blender/makesrna/intern/rna_workspace.c
@@ -49,6 +49,7 @@
 
 #include "DNA_object_types.h"
 #include "DNA_screen_types.h"
+#include "DNA_space_types.h"
 
 #include "RNA_access.h"
 
@@ -107,6 +108,42 @@ static void rna_WorkSpace_owner_ids_clear(
 	WM_main_add_notifier(NC_OBJECT | ND_MODIFIER | NA_REMOVED, workspace);
 }
 
+static bToolRef *rna_WorkSpace_tools_from_tkey(WorkSpace *workspace, const bToolKey *tkey, bool create)
+{
+	if (create) {
+		bToolRef *tref;
+		WM_toolsystem_ref_ensure(workspace, tkey, &tref);
+		return tref;
+	}
+	return WM_toolsystem_ref_find(workspace, tkey);
+}
+
+static bToolRef *rna_WorkSpace_tools_from_space_view3d_mode(
+        WorkSpace *workspace, int mode, int create)
+{
+	return rna_WorkSpace_tools_from_tkey(workspace, &(bToolKey){ .space_type = SPACE_VIEW3D, .mode = mode}, create);
+}
+
+static bToolRef *rna_WorkSpace_tools_from_space_image_mode(
+        WorkSpace *workspace, int mode, int create)
+{
+	return rna_WorkSpace_tools_from_tkey(workspace, &(bToolKey){ .space_type = SPACE_IMAGE, .mode = mode}, create);
+}
+
+const EnumPropertyItem *rna_WorkSpace_tools_mode_itemf(
+        bContext *UNUSED(C), PointerRNA *ptr, PropertyRNA *UNUSED(prop), bool *UNUSED(r_free))
+{
+	WorkSpace *workspace = ptr->id.data;
+
+	switch (workspace->tools_space_type) {
+		case SPACE_VIEW3D:
+			return rna_enum_object_mode_items;
+		case SPACE_IMAGE:
+			return rna_enum_space_image_mode_items;
+	}
+	return DummyRNA_NULL_items;
+}
+
 #else /* RNA_RUNTIME */
 
 static void rna_def_workspace_owner(BlenderRNA *brna)
@@ -159,6 +196,56 @@ static void rna_def_workspace_owner_ids(BlenderRNA *brna, PropertyRNA *cprop)
 	RNA_def_function_ui_description(func, "Remove all tags");
 }
 
+static void rna_def_workspace_tool(BlenderRNA *brna)
+{
+	StructRNA *srna;
+	PropertyRNA *prop;
+
+	srna = RNA_def_struct(brna, "WorkspaceTool", NULL);
+	RNA_def_struct_sdna(srna, "bToolRef");
+	RNA_def_struct_clear_flag(srna, STRUCT_UNDO);
+	RNA_def_struct_ui_text(srna, "Work Space Tool", "");
+
+	prop = RNA_def_property(srna, "name", PROP_STRING, PROP_NONE);
+	RNA_def_property_string_sdna(prop, NULL, "idname");
+	RNA_def_property_ui_text(prop, "Name", "");
+	RNA_def_struct_name_property(srna, prop);
+
+	RNA_api_workspace_tool(srna);
+}
+
+static void rna_def_workspace_tools(BlenderRNA *brna, PropertyRNA *cprop)
+{
+	StructRNA *srna;
+
+	FunctionRNA *func;
+	PropertyRNA *parm;
+
+	RNA_def_property_srna(cprop, "wmTools");
+	srna = RNA_def_struct(brna, "wmTools", NULL);
+	RNA_def_struct_sdna(srna, "WorkSpace");
+	RNA_def_struct_ui_text(srna, "WorkSpace UI Tags", "");
+
+	/* add owner_id */
+	func = RNA_def_function(srna, "from_space_view3d_mode", "rna_WorkSpace_tools_from_space_view3d_mode");
+	RNA_def_function_ui_description(func, "");
+	parm = RNA_def_enum(func, "mode", rna_enum_object_mode_items, 0, "", "");
+	RNA_def_parameter_flags(parm, 0, PARM_REQUIRED);
+	RNA_def_boolean(func, "create", false, "Create", "");
+	/* return type */
+	parm = RNA_def_pointer(func, "result", "WorkspaceTool", "", "");
+	RNA_def_function_return(func, parm);
+
+	func = RNA_def_function(srna, "from_space_image_mode", "rna_WorkSpace_tools_from_space_image_mode");
+	RNA_def_function_ui_description(func, "");
+	parm = RNA_def_enum(func, "mode", rna_enum_space_image_mode_items, 0, "", "");
+	RNA_def_parameter_flags(parm, 0, PARM_REQUIRED);
+	RNA_def_boolean(func, "create", false, "Create", "");
+	/* return type */
+	parm = RNA_def_pointer(func, "result", "WorkspaceTool", "", "");
+	RNA_def_function_return(func, parm);
+}
+
 static void rna_def_workspace(BlenderRNA *brna)
 {
 	StructRNA *srna;
@@ -177,36 +264,29 @@ static void rna_def_workspace(BlenderRNA *brna)
 	                                  "rna_workspace_screens_item_get", NULL, NULL, NULL, NULL);
 	RNA_def_property_ui_text(prop, "Screens", "Screen layouts of a workspace");
 
-	prop = RNA_def_property(srna, "tool_keymap", PROP_STRING, PROP_NONE);
-	RNA_def_property_string_sdna(prop, NULL, "tool.keymap");
-	RNA_def_property_ui_text(prop, "Active Tool", "Currently active tool keymap");
-	RNA_def_property_clear_flag(prop, PROP_EDITABLE);
-
-	prop = RNA_def_property(srna, "tool_manipulator_group", PROP_STRING, PROP_NONE);
-	RNA_def_property_string_sdna(prop, NULL, "tool.manipulator_group");
-	RNA_def_property_ui_text(prop, "Active Tool", "Currently active tool manipulator");
-	RNA_def_property_clear_flag(prop, PROP_EDITABLE);
-
-	prop = RNA_def_property(srna, "tool_data_block", PROP_STRING, PROP_NONE);
-	RNA_def_property_string_sdna(prop, NULL, "tool.data_block");
-	RNA_def_property_ui_text(prop, "Active Tool", "Currently active data-block");
-	RNA_def_property_clear_flag(prop, PROP_EDITABLE);
+	prop = RNA_def_property(srna, "owner_ids", PROP_COLLECTION, PROP_NONE);
+	RNA_def_property_struct_type(prop, "wmOwnerID");
+	RNA_def_property_ui_text(prop, "UI Tags", "");
+	rna_def_workspace_owner_ids(brna, prop);
 
-	prop = RNA_def_property(srna, "tool_index", PROP_INT, PROP_NONE);
-	RNA_def_property_int_sdna(prop, NULL, "tool.index");
-	RNA_def_property_ui_text(prop, "Active Tool Index", "Tool group index");
-	RNA_def_property_clear_flag(prop, PROP_EDITABLE);
+	prop = RNA_def_property(srna, "tools", PROP_COLLECTION, PROP_NONE);
+	RNA_def_property_collection_sdna(prop, NULL, "tools", NULL);
+	RNA_def_property_struct_type(prop, "WorkspaceTool");
+	RNA_def_property_ui_text(prop, "Tools", "");
+	rna_def_workspace_tools(brna, prop);
 
-	prop = RNA_def_property(srna, "tool_space_type", PROP_ENUM, PROP_NONE);
-	RNA_def_property_enum_sdna(prop, NULL, "tool.spacetype");
+	prop = RNA_def_property(srna, "tools_space_type", PROP_ENUM, PROP_NONE);
+	RNA_def_property_enum_sdna(prop, NULL, "tools_space_type");
 	RNA_def_property_enum_items(prop, rna_enum_space_type_items);
 	RNA_def_property_ui_text(prop, "Active Tool Space", "Tool space type");
 	RNA_def_property_clear_flag(prop, PROP_EDITABLE);
 
-	prop = RNA_def_property(srna, "owner_ids", PROP_COLLECTION, PROP_NONE);
-	RNA_def_property_struct_type(prop, "wmOwnerID");
-	RNA_def_property_ui_text(prop, "UI Tags", "");
-	rna_def_workspace_owner_ids(brna, prop);
+	prop = RNA_def_property(srna, "tools_mode", PROP_ENUM, PROP_NONE);
+	RNA_def_property_enum_sdna(prop, NULL, "tools_mode");
+	RNA_def_property_enum_items(prop, rna_enum_object_mode_items);  /* value is placeholder, itemf is used. */
+	RNA_def_property_enum_funcs(prop, NULL, NULL, "rna_WorkSpace_tools_mode_itemf");
+	RNA_def_property_ui_text(prop, "Active Tool Space", "Tool mode");
+	RNA_def_property_clear_flag(prop, PROP_EDITABLE);
 
 #if 0
 	prop = RNA_def_property(srna, "object_mode", PROP_ENUM, PROP_NONE);
@@ -221,11 +301,15 @@ static void rna_def_workspace(BlenderRNA *brna)
 	RNA_def_property_ui_text(prop, "Use UI Tags",
 	                         "Filter the UI by tags");
 	RNA_def_property_update(prop, 0, "rna_window_update_all");
+
+	RNA_api_workspace(srna);
 }
 
 void RNA_def_workspace(BlenderRNA *brna)
 {
 	rna_def_workspace_owner(brna);
+	rna_def_workspace_tool(brna);
+
 	rna_def_workspace(brna);
 }
 
diff --git a/source/blender/makesrna/intern/rna_workspace_api.c b/source/blender/makesrna/intern/rna_workspace_api.c
new file mode 100644
index 00000000000..4b0e2b5918e
--- /dev/null
+++ b/source/blender/makesrna/intern/rna_workspace_api.c
@@ -0,0 +1,90 @@
+/*
+ * ***** BEGIN GPL LICENSE BLOCK *****
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ *
+ * ***** END GPL LICENSE BLOCK *****
+ */
+
+/** \file blender/makesrna/intern/rna_workspace_api.c
+ *  \ingroup RNA
+ */
+
+
+#include <stdlib.h>
+#include <stdio.h>
+#include <string.h>
+#include <time.h>
+
+#include "BLI_utildefines.h"
+
+#include "RNA_define.h"
+
+#include "DNA_object_types.h"
+#include "DNA_windowmanager_types.h"
+
+#include "rna_internal.h"  /* own include */
+
+#ifdef RNA_RUNTIME
+
+static void rna_WorkspaceTool_setup(
+        ID *id,
+        bToolRef *tref,
+        bContext *C,
+        const char *name,
+        /* Args for: 'bToolRef_Runtime'. */
+        const char *keymap,
+        const char *manipulator_group,
+        const char *data_block,
+        int index)
+{
+	bToolRef_Runtime tref_rt = {0};
+
+	STRNCPY(tref_rt.keymap, keymap);
+	STRNCPY(tref_rt.manipulator_group, manipulator_group);
+	STRNCPY(tref_rt.data_block, data_block);
+	tref_rt.index = index;
+
+	WM_toolsystem_ref_set_from_runtime(C, (WorkSpace *)id, tref, &tref_rt, name);
+}
+
+#else
+
+void RNA_api_workspace(StructRNA *UNUSED(srna))
+{
+	/* FunctionRNA *func; */
+	/* PropertyRNA *parm; */
+}
+
+void RNA_api_workspace_tool(StructRNA *srna)
+{
+	PropertyRNA *parm;
+	FunctionRNA *func;
+
+	func = RNA_def_function(srna, "setup", "rna_WorkspaceTool_setup");
+	RNA_def_function_flag(func, FUNC_USE_SELF_ID | FUNC_USE_CONTEXT);
+	RNA_def_function_ui_description(func, "Set the tool settings");
+
+	parm = RNA_def_string(func, "name", NULL, KMAP_MAX_NAME, "Name", "");
+	RNA_def_parameter_flags(parm, 0, PARM_REQUIRED);
+
+	/* 'bToolRef_Runtime' */
+	RNA_def_string(func, "keymap", NULL, KMAP_MAX_NAME, "Key Map", "");
+	RNA_def_string(func, "manipulator_group", NULL, MAX_NAME, "Manipulator Group", "");
+	RNA_def_string(func, "data_block", NULL, MAX_NAME, "Data Block", "");
+	RNA_def_int(func, "index", 0, INT_MIN, INT_MAX, "Index", "", INT_MIN, INT_MAX);
+}
+
+#endif
diff --git a/source/blender/windowmanager/WM_api.h b/source/blender/windowmanager/WM_api.h
index 9176385c40d..5562e7880fa 100644
--- a/source/blender/windowmanager/WM_api.h
+++ b/source/blender/windowmanager/WM_api.h
@@ -47,6 +47,7 @@ extern "C" {
 #endif
 
 struct bContext;
+struct bToolRef_Runtime;
 struct GHashIterator;
 struct IDProperty;
 struct wmEvent;
@@ -595,13 +596,45 @@ bool        WM_event_is_ime_switch(const struct wmEvent *event);
 #endif
 
 /* wm_toolsystem.c  */
-void WM_toolsystem_unlink(struct bContext *C, struct WorkSpace *workspace);
-void WM_toolsystem_link(struct bContext *C, struct WorkSpace *workspace);
-void WM_toolsystem_refresh(struct bContext *C, struct WorkSpace *workspace);
 
-void WM_toolsystem_set(struct bContext *C, const struct bToolDef *tool);
+/* Values that define a categoey of active tool. */
+typedef struct bToolKey { int space_type; int mode; } bToolKey;
+
+struct bToolRef *WM_toolsystem_ref_from_context(struct bContext *C);
+struct bToolRef *WM_toolsystem_ref_find(struct WorkSpace *workspace, const bToolKey *tkey);
+bool WM_toolsystem_ref_ensure(
+        struct WorkSpace *workspace, const bToolKey *tkey,
+        struct bToolRef **r_tref);
+
+struct bToolRef_Runtime *WM_toolsystem_runtime_from_context(struct bContext *C);
+struct bToolRef_Runtime *WM_toolsystem_runtime_find(struct WorkSpace *workspace, const bToolKey *tkey);
+
+void WM_toolsystem_unlink(struct bContext *C, struct WorkSpace *workspace, const bToolKey *tkey);
+void WM_toolsystem_link(struct bContext *C, struct WorkSpace *workspace, const bToolKey *tkey);
+void WM_toolsystem_refresh(struct bContext *C, struct WorkSpace *workspace, const bToolKey *tkey);
+
+void WM_toolsystem_unlink_all(struct bContext *C, struct WorkSpace *workspace);
+void WM_toolsystem_link_all(struct bContext *C, struct WorkSpace *workspace);
+void WM_toolsystem_refresh_all(struct bContext *C, struct WorkSpace *workspace);
+
+void WM_toolsystem_ref_set_from_runtime(
+        struct bContext *C, struct WorkSpace *workspace, struct bToolRef *tref,
+        const struct bToolRef_Runtime *tool, const char *idname);
+
 void WM_toolsystem_init(struct bContext *C);
 
+int WM_toolsystem_mode_from_spacetype(
+        struct WorkSpace *workspace, struct Scene *scene, struct ScrArea *sa,
+        int space_type);
+bool WM_toolsystem_key_from_context(
+        struct WorkSpace *workspace, struct Scene *scene, struct ScrArea *sa,
+        bToolKey *tkey);
+void WM_toolsystem_update_from_context(
+        struct bContext *C,
+        struct WorkSpace *workspace, struct Scene *scene, struct ScrArea *sa);
+
+void WM_toolsystem_update_from_context_view3d(struct bContext *C);
+
 bool WM_toolsystem_active_tool_is_brush(const struct bContext *C);
 
 void WM_toolsystem_do_msg_notify_tag_refresh(
diff --git a/source/blender/windowmanager/intern/wm_event_system.c b/source/blender/windowmanager/intern/wm_event_system.c
index 7963bf16534..8bbbd1b60df 100644
--- a/source/blender/windowmanager/intern/wm_event_system.c
+++ b/source/blender/windowmanager/intern/wm_event_system.c
@@ -2875,11 +2875,14 @@ void wm_event_do_handlers(bContext *C)
 									wmEventHandler sneaky_handler = {NULL};
 									if (ar->regiontype == RGN_TYPE_WINDOW) {
 										WorkSpace *workspace = WM_window_get_active_workspace(win);
-										if (workspace->tool.keymap[0] &&
-										    workspace->tool.spacetype == sa->spacetype)
-										{
+										const bToolKey tkey = {
+											.space_type = sa->spacetype,
+											.mode = WM_toolsystem_mode_from_spacetype(workspace, win->scene, sa, sa->spacetype),
+										};
+										bToolRef_Runtime *tref_rt = WM_toolsystem_runtime_find(workspace, &tkey);
+										if (tref_rt && tref_rt->keymap[0]) {
 											wmKeyMap *km = WM_keymap_find_all(
-											        C, workspace->tool.keymap, sa->spacetype, RGN_TYPE_WINDOW);
+											        C, tref_rt->keymap, sa->spacetype, RGN_TYPE_WINDOW);
 											if (km != NULL) {
 												sneaky_handler.keymap = km;
 												/* Handle widgets first. */
diff --git a/source/blender/windowmanager/intern/wm_operators.c b/source/blender/windowmanager/intern/wm_operators.c
index a154f6b83ea..22133ae1602 100644
--- a/source/blender/windowmanager/intern/wm_operators.c
+++ b/source/blender/windowmanager/intern/wm_operators.c
@@ -1826,69 +1826,6 @@ static void WM_OT_operator_defaults(wmOperatorType *ot)
 	ot->flag = OPTYPE_INTERNAL;
 }
 
-#ifdef USE_WORKSPACE_TOOL
-/* ***************** Set Active Tool ************************* */
-
-/* Developers note: in it's current form this doesn't need to be an operator,
- * keep this as-is for now since it may end up setting an active key-map.
- */
-
-static int wm_operator_tool_set_exec(bContext *C, wmOperator *op)
-{
-	ScrArea *sa = CTX_wm_area(C);
-
-	bToolDef tool_def = {{0}};
-
-	{
-		PropertyRNA *prop = RNA_struct_find_property(op->ptr, "space_type");
-		if (RNA_property_is_set(op->ptr, prop)) {
-			tool_def.spacetype = RNA_property_enum_get(op->ptr, prop);
-		}
-		else {
-			if (sa == NULL) {
-				BKE_report(op->reports, RPT_ERROR, "Space type not set");
-				return OPERATOR_CANCELLED;
-			}
-			tool_def.spacetype = sa->spacetype;
-		}
-	}
-
-	tool_def.index = RNA_int_get(op->ptr, "index");
-	RNA_string_get(op->ptr, "keymap", tool_def.keymap);
-	RNA_string_get(op->ptr, "manipulator_group", tool_def.manipulator_group);
-	RNA_string_get(op->ptr, "data_block", tool_def.data_block);
-
-	WM_toolsystem_set(C, &tool_def);
-
-	/* For some reason redraw fails with menus (even though 'ar' isn't the menu's region). */
-	if (sa) {
-		ED_area_tag_redraw(sa);
-	}
-	else {
-		WM_event_add_notifier(C, NC_WINDOW, NULL);
-	}
-
-	return OPERATOR_FINISHED;
-}
-
-static void WM_OT_tool_set(wmOperatorType *ot)
-{
-	ot->name = "Set Active Tool";
-	ot->idname = "WM_OT_tool_set";
-	ot->description = "Set the active tool";
-
-	ot->exec = wm_operator_tool_set_exec;
-
-	ot->flag = OPTYPE_INTERNAL;
-
-	RNA_def_enum(ot->srna, "space_type", rna_enum_space_type_items + 1, SPACE_EMPTY, "Space Type", "");
-	RNA_def_string(ot->srna, "keymap", NULL, KMAP_MAX_NAME, "Key Map", "");
-	RNA_def_string(ot->srna, "manipulator_group", NULL, MAX_NAME, "Manipulator Group", "");
-	RNA_def_string(ot->srna, "data_block", NULL, MAX_NAME, "Data Block", "");
-	RNA_def_int(ot->srna, "index", 0, INT_MIN, INT_MAX, "Index", "", INT_MIN, INT_MAX);
-}
-#endif /* USE_WORKSPACE_TOOL */
-
 /* ***************** Splash Screen ************************* */
 
 static void wm_block_splash_close(bContext *C, void *arg_block, void *UNUSED(arg))
@@ -3765,9 +3702,6 @@ void wm_operatortype_init(void)
 	WM_operatortype_append(WM_OT_memory_statistics);
 	WM_operatortype_append(WM_OT_debug_menu);
 	WM_operatortype_append(WM_OT_operator_defaults);
-#ifdef USE_WORKSPACE_TOOL
-	WM_operatortype_append(WM_OT_tool_set);
-#endif
 	WM_operatortype_append(WM_OT_splash);
 	WM_operatortype_append(WM_OT_search_menu);
 	WM_operatortype_append(WM_OT_call_menu);
diff --git a/source/blender/windowmanager/intern/wm_toolsystem.c b/source/blender/windowmanager/intern/wm_toolsystem.c
index c351d0fd849..24b902a6a92 100644
--- a/source/blender/windowmanager/intern/wm_toolsystem.c
+++ b/source/blender/windowmanager/intern/wm_toolsystem.c
@@ -28,13 +28,18 @@
 
 #include "CLG_log.h"
 
+#include "MEM_guardedalloc.h"
+
 #include "BLI_utildefines.h"
 #include "BLI_string.h"
+#include "BLI_listbase.h"
 
 #include "DNA_ID.h"
 #include "DNA_scene_types.h"
+#include "DNA_space_types.h"
 #include "DNA_windowmanager_types.h"
 #include "DNA_workspace_types.h"
+#include "DNA_object_types.h"
 
 #include "BKE_context.h"
 #include "BKE_library.h"
@@ -48,16 +53,80 @@
 #include "WM_types.h"
 #include "WM_message.h"
 
-void WM_toolsystem_unlink(bContext *C, WorkSpace *workspace)
+
+/* -------------------------------------------------------------------- */
+/** \name Tool Reference API
+ * \{ */
+
+struct bToolRef *WM_toolsystem_ref_from_context(struct bContext *C)
 {
-	Main *bmain = CTX_data_main(C);
-	wmWindowManager *wm = bmain->wm.first;
+	WorkSpace *workspace = CTX_wm_workspace(C);
+	Scene *scene = CTX_data_scene(C);
+	ScrArea *sa = CTX_wm_area(C);
+	const bToolKey tkey = {
+		.space_type = sa->spacetype,
+		.mode = WM_toolsystem_mode_from_spacetype(workspace, scene, sa, sa->spacetype),
+	};
+	return WM_toolsystem_ref_find(workspace, &tkey);
+}
+
+struct bToolRef_Runtime *WM_toolsystem_runtime_from_context(struct bContext *C)
+{
+	bToolRef *tref = WM_toolsystem_ref_from_context(C);
+	return tref ? tref->runtime : NULL;
+}
+
+bToolRef *WM_toolsystem_ref_find(WorkSpace *workspace, const bToolKey *tkey)
+{
+	LISTBASE_FOREACH (bToolRef *, tref, &workspace->tools) {
+		if ((tref->space_type == tkey->space_type) &&
+		    (tref->mode == tkey->mode))
+		{
+			return tref;
+		}
+	}
+	return NULL;
+}
+
+bToolRef_Runtime *WM_toolsystem_runtime_find(WorkSpace *workspace, const bToolKey *tkey)
+{
+	bToolRef *tref = WM_toolsystem_ref_find(workspace, tkey);
+	return tref ? tref->runtime : NULL;
+}
+
+bool WM_toolsystem_ref_ensure(
+        struct WorkSpace *workspace, const bToolKey *tkey,
+        bToolRef **r_tref)
+{
+	bToolRef *tref = WM_toolsystem_ref_find(workspace, tkey);
+	if (tref) {
+		*r_tref = tref;
+		return false;
+	}
+	tref = MEM_callocN(sizeof(*tref), __func__);
+	BLI_addhead(&workspace->tools, tref);
+	tref->space_type = tkey->space_type;
+	tref->mode = tkey->mode;
+	*r_tref = tref;
+	return true;
+}
+
+/** \} */
+
+
+static void toolsystem_unlink_ref(bContext *C, WorkSpace *workspace, bToolRef *tref)
+{
+	bToolRef_Runtime *tref_rt = tref->runtime;
 
-	if (workspace->tool.manipulator_group[0]) {
-		wmManipulatorGroupType *wgt = WM_manipulatorgrouptype_find(workspace->tool.manipulator_group, false);
+	if (tref_rt->manipulator_group[0]) {
+		wmManipulatorGroupType *wgt = WM_manipulatorgrouptype_find(tref_rt->manipulator_group, false);
 		if (wgt != NULL) {
 			bool found = false;
 
+			/* TODO(campbell) */
+			Main *bmain = CTX_data_main(C);
+#if 0
+			wmWindowManager *wm = bmain->wm.first;
 			/* Check another workspace isn't using this tool. */
 			for (wmWindow *win = wm->windows.first; win; win = win->next) {
 				const WorkSpace *workspace_iter = WM_window_get_active_workspace(win);
@@ -68,7 +137,9 @@ void WM_toolsystem_unlink(bContext *C, WorkSpace *workspace)
 					}
 				}
 			}
-
+#else
+			UNUSED_VARS(workspace);
+#endif
 			if (!found) {
 				wmManipulatorMapType *mmap_type = WM_manipulatormaptype_ensure(&wgt->mmap_params);
 				WM_manipulatormaptype_group_unlink(C, bmain, mmap_type, wgt);
@@ -76,11 +147,19 @@ void WM_toolsystem_unlink(bContext *C, WorkSpace *workspace)
 		}
 	}
 }
+void WM_toolsystem_unlink(bContext *C, WorkSpace *workspace, const bToolKey *tkey)
+{
+	bToolRef *tref = WM_toolsystem_ref_find(workspace, tkey);
+	if (tref && tref->runtime) {
+		toolsystem_unlink_ref(C, workspace, tref);
+	}
+}
 
-void WM_toolsystem_link(bContext *C, WorkSpace *workspace)
+static void toolsystem_ref_link(bContext *C, WorkSpace *workspace, bToolRef *tref)
 {
-	if (workspace->tool.manipulator_group[0]) {
-		const char *idname = workspace->tool.manipulator_group;
+	bToolRef_Runtime *tref_rt = tref->runtime;
+	if (tref_rt->manipulator_group[0]) {
+		const char *idname = tref_rt->manipulator_group;
 		wmManipulatorGroupType *wgt = WM_manipulatorgrouptype_find(idname, false);
 		if (wgt != NULL) {
 			WM_manipulator_group_type_ensure_ptr(wgt);
@@ -90,11 +169,11 @@ void WM_toolsystem_link(bContext *C, WorkSpace *workspace)
 		}
 	}
 
-	if (workspace->tool.data_block[0]) {
+	if (tref_rt->data_block[0]) {
 		Main *bmain = CTX_data_main(C);
 
 		/* Currently only brush data-blocks supported. */
-		struct Brush *brush = (struct Brush *)BKE_libblock_find_name(ID_BR, workspace->tool.data_block);
+		struct Brush *brush = (struct Brush *)BKE_libblock_find_name(ID_BR, tref_rt->data_block);
 
 		if (brush) {
 			wmWindowManager *wm = bmain->wm.first;
@@ -113,34 +192,82 @@ void WM_toolsystem_link(bContext *C, WorkSpace *workspace)
 		}
 	}
 }
+void WM_toolsystem_link(bContext *C, WorkSpace *workspace, const bToolKey *tkey)
+{
+	bToolRef *tref = WM_toolsystem_ref_find(workspace, tkey);
+	if (tref) {
+		toolsystem_ref_link(C, workspace, tref);
+	}
+}
 
-void WM_toolsystem_refresh(bContext *C, WorkSpace *workspace)
+static void toolsystem_refresh_ref(bContext *C, WorkSpace *workspace, bToolRef *tref)
+{
+	/* currently same operation. */
+	toolsystem_ref_link(C, workspace, tref);
+}
+void WM_toolsystem_refresh(bContext *C, WorkSpace *workspace, const bToolKey *tkey)
 {
-	WM_toolsystem_link(C, workspace);
+	bToolRef *tref = WM_toolsystem_ref_find(workspace, tkey);
+	if (tref) {
+		toolsystem_refresh_ref(C, workspace, tref);
+	}
 }
 
-void WM_toolsystem_set(bContext *C, const bToolDef *tool)
+/* Operate on all active tools. */
+void WM_toolsystem_unlink_all(struct bContext *C, struct WorkSpace *workspace)
 {
-	WorkSpace *workspace = CTX_wm_workspace(C);
+	LISTBASE_FOREACH (bToolRef *, tref, &workspace->tools) {
+		if (tref->runtime) {
+			toolsystem_unlink_ref(C, workspace, tref);
+		}
+	}
+}
+void WM_toolsystem_link_all(struct bContext *C, struct WorkSpace *workspace)
+{
+	LISTBASE_FOREACH (bToolRef *, tref, &workspace->tools) {
+		if (tref->runtime) {
+			toolsystem_ref_link(C, workspace, tref);
+		}
+	}
+}
+void WM_toolsystem_refresh_all(struct bContext *C, struct WorkSpace *workspace)
+{
+	LISTBASE_FOREACH (bToolRef *, tref, &workspace->tools) {
+		if (tref->runtime) {
+			toolsystem_refresh_ref(C, workspace, tref);
+		}
+	}
+}
+
+void WM_toolsystem_ref_set_from_runtime(
+        struct bContext *C, struct WorkSpace *workspace, bToolRef *tref,
+        const bToolRef_Runtime *tref_rt, const char *idname)
+{
+	if (tref->runtime) {
+		toolsystem_unlink_ref(C, workspace, tref);
+	}
 
-	WM_toolsystem_unlink(C, workspace);
+	STRNCPY(tref->idname, idname);
 
-	workspace->tool.index = tool->index;
-	workspace->tool.spacetype = tool->spacetype;
+	/* BAD DESIGN WARNING: used for topbar. */
+	workspace->tools_space_type = tref->space_type;
+	workspace->tools_mode = tref->mode;
 
-	if (&workspace->tool != tool) {
-		STRNCPY(workspace->tool.keymap, tool->keymap);
-		STRNCPY(workspace->tool.manipulator_group, tool->manipulator_group);
-		STRNCPY(workspace->tool.data_block, tool->data_block);
-		workspace->tool.spacetype = tool->spacetype;
+	if (tref->runtime == NULL) {
+		tref->runtime = MEM_callocN(sizeof(*tref->runtime), __func__);
 	}
 
-	WM_toolsystem_link(C, workspace);
+	if (tref_rt != tref->runtime) {
+		*tref->runtime = *tref_rt;
+	}
 
+	toolsystem_ref_link(C, workspace, tref);
+
+	/* TODO(campbell): fix message. */
 	{
 		struct wmMsgBus *mbus = CTX_wm_message_bus(C);
 		WM_msg_publish_rna_prop(
-		        mbus, &workspace->id, workspace, WorkSpace, tool_keymap);
+		        mbus, &workspace->id, workspace, WorkSpace, tools);
 	}
 }
 
@@ -151,8 +278,84 @@ void WM_toolsystem_init(bContext *C)
 
 	for (wmWindow *win = wm->windows.first; win; win = win->next) {
 		WorkSpace *workspace = WM_window_get_active_workspace(win);
-		WM_toolsystem_link(C, workspace);
+		WM_toolsystem_link_all(C, workspace);
+	}
+}
+
+int WM_toolsystem_mode_from_spacetype(
+        WorkSpace *workspace, Scene *scene, ScrArea *sa,
+        int spacetype)
+{
+	int mode = -1;
+	switch (spacetype) {
+		case SPACE_VIEW3D:
+		{
+			/* 'sa' may be NULL in this case. */
+			ViewLayer *view_layer = BKE_workspace_view_layer_get(workspace, scene);
+			Object *obact = OBACT(view_layer);
+			mode = obact ? obact->mode : OB_MODE_OBJECT;
+			break;
+		}
+		case SPACE_IMAGE:
+		{
+			SpaceImage *sima = sa->spacedata.first;
+			mode = sima->mode;
+			break;
+		}
 	}
+	return mode;
+}
+
+bool WM_toolsystem_key_from_context(
+        WorkSpace *workspace, Scene *scene, ScrArea *sa,
+        bToolKey *tkey)
+{
+	int space_type = SPACE_EMPTY;
+	int mode = -1;
+
+	if (sa != NULL) {
+		space_type = sa->spacetype;
+		mode = WM_toolsystem_mode_from_spacetype(workspace, scene, sa, space_type);
+	}
+
+	if (mode != -1) {
+		tkey->space_type = space_type;
+		tkey->mode = mode;
+		return true;
+	}
+	return false;
+}
+
+/**
+ * Run after changing modes.
+ */
+static void toolsystem_update_with_toolref(
+        bContext *C, WorkSpace *workspace, const bToolKey *tkey, const char *default_tool)
+{
+	bToolRef *tref;
+	if (WM_toolsystem_ref_ensure(workspace, tkey, &tref)) {
+		STRNCPY(tref->idname, default_tool);
+	}
+
+	wmOperatorType *ot = WM_operatortype_find("WM_OT_tool_set_by_name", false);
+	PointerRNA op_props;
+	WM_operator_properties_create_ptr(&op_props, ot);
+	RNA_string_set(&op_props, "name", tref->idname);
+	RNA_enum_set(&op_props, "space_type", tkey->space_type);
+	WM_operator_name_call_ptr(C, ot, WM_OP_EXEC_DEFAULT, &op_props);
+	WM_operator_properties_free(&op_props);
+}
+
+void WM_toolsystem_update_from_context_view3d(bContext *C)
+{
+	WorkSpace *workspace = CTX_wm_workspace(C);
+	Scene *scene = CTX_data_scene(C);
+	int space_type = SPACE_VIEW3D;
+	const bToolKey tkey = {
+		.space_type = space_type,
+		.mode = WM_toolsystem_mode_from_spacetype(workspace, scene, NULL, space_type),
+	};
+	toolsystem_update_with_toolref(C, workspace, &tkey, "Cursor");
 }
 
 /**
@@ -160,15 +363,21 @@ void WM_toolsystem_init(bContext *C)
  */
 bool WM_toolsystem_active_tool_is_brush(const bContext *C)
 {
-	WorkSpace *workspace = CTX_wm_workspace(C);
-	/* Will need to become more comprehensive, for now check tool data-block. */
-	return workspace->tool.data_block[0] != '\0';
+	bToolRef_Runtime *tref_rt = WM_toolsystem_runtime_from_context((bContext *)C);
+	return tref_rt->data_block[0] != '\0';
 }
 
 /* Follow wmMsgNotifyFn spec */
 void WM_toolsystem_do_msg_notify_tag_refresh(
-        bContext *C, wmMsgSubscribeKey *UNUSED(msg_key), wmMsgSubscribeValue *UNUSED(msg_val))
+        bContext *C, wmMsgSubscribeKey *UNUSED(msg_key), wmMsgSubscribeValue *msg_val)
 {
 	WorkSpace *workspace = CTX_wm_workspace(C);
-	WM_toolsystem_refresh(C, workspace);
+	Scene *scene = CTX_data_scene(C);
+	ScrArea *sa = msg_val->user_data;
+	int space_type = sa->spacetype;
+	const bToolKey tkey = {
+		.space_type = space_type,
+		.mode = WM_toolsystem_mode_from_spacetype(workspace, scene, sa, sa->spacetype),
+	};
+	WM_toolsystem_refresh(C, workspace, &tkey);
 }