Workspaces: add main and child windows.

* Main windows show a topbar and statusbar, and select a workspace and
  scene. They are created with Window > New Main Window.

* Child windows do not show a topbar or statusbar. These follow the
  workspace and scene of their parent main window. Created with Window >
  New Window or View > Duplicate Area into New Window.

* The purpose of this change is to support multi monitor setups where you
  just want to put more editors on the other monitors. Without multiple
  topbars and statusbars, working within a single workspace and scene.
  Creating multiple main windows is intended to be a concious choice to
  do different tasks in different workspaces and scenes.

* Note these changes do not currently affect how the operating system
  treats the windows.

* When changing the workspace, the layout in all child windows changes.
  This makes sense if we consider child windows to be just a way to
  extend the main window across more monitors. In some case it may be
  useful to keep the same layout though, we can add an option for this
  depending on user feedback.

1 files changed, 103 insertions, 58 deletions

diff --git a/source/blender/windowmanager/intern/wm_window.c b/source/blender/windowmanager/intern/wm_window.c
index 43231855162..d28d2c6b001 100644
--- a/source/blender/windowmanager/intern/wm_window.c
+++ b/source/blender/windowmanager/intern/wm_window.c
@@ -256,7 +256,7 @@ static int find_free_winid(wmWindowManager *wm)
 }
 
 /* don't change context itself */
-wmWindow *wm_window_new(bContext *C)
+wmWindow *wm_window_new(bContext *C, wmWindow *parent)
 {
 	Main *bmain = CTX_data_main(C);
 	wmWindowManager *wm = CTX_wm_manager(C);
@@ -265,6 +265,7 @@ wmWindow *wm_window_new(bContext *C)
 	BLI_addtail(&wm->windows, win);
 	win->winid = find_free_winid(wm);
 
+	win->parent = (parent && parent->parent) ? parent->parent : parent;
 	win->stereo3d_format = MEM_callocN(sizeof(Stereo3dFormat), "Stereo 3D Format (window)");
 	win->workspace_hook = BKE_workspace_instance_hook_create(bmain);
 
@@ -272,10 +273,11 @@ wmWindow *wm_window_new(bContext *C)
 }
 
 /* part of wm_window.c api */
-wmWindow *wm_window_copy(bContext *C, wmWindow *win_src, const bool duplicate_layout)
+wmWindow *wm_window_copy(bContext *C, wmWindow *win_src, const bool duplicate_layout, const bool child)
 {
 	Main *bmain = CTX_data_main(C);
-	wmWindow *win_dst = wm_window_new(C);
+	wmWindow *win_parent = (child) ? win_src : win_src->parent;
+	wmWindow *win_dst = wm_window_new(C, win_parent);
 	WorkSpace *workspace = WM_window_get_active_workspace(win_src);
 	WorkSpaceLayout *layout_old = WM_window_get_active_layout(win_src);
 	Scene *scene = WM_window_get_active_scene(win_src);
@@ -287,9 +289,9 @@ wmWindow *wm_window_copy(bContext *C, wmWindow *win_src, const bool duplicate_la
 	win_dst->sizey = win_src->sizey;
 
 	win_dst->scene = scene;
-	WM_window_set_active_workspace(win_dst, workspace);
+	BKE_workspace_active_set(win_dst->workspace_hook, workspace);
 	layout_new = duplicate_layout ? ED_workspace_layout_duplicate(bmain, workspace, layout_old, win_dst) : layout_old;
-	WM_window_set_active_layout(win_dst, workspace, layout_new);
+	BKE_workspace_hook_layout_for_workspace_set(win_dst->workspace_hook, workspace, layout_new);
 
 	*win_dst->stereo3d_format = *win_src->stereo3d_format;
 
@@ -300,12 +302,12 @@ wmWindow *wm_window_copy(bContext *C, wmWindow *win_src, const bool duplicate_la
  * A higher level version of copy that tests the new window can be added.
  * (called from the operator directly)
  */
-wmWindow *wm_window_copy_test(bContext *C, wmWindow *win_src, const bool duplicate_layout)
+wmWindow *wm_window_copy_test(bContext *C, wmWindow *win_src, const bool duplicate_layout, const bool child)
 {
 	wmWindowManager *wm = CTX_wm_manager(C);
 	wmWindow *win_dst;
 
-	win_dst = wm_window_copy(C, win_src, duplicate_layout);
+	win_dst = wm_window_copy(C, win_src, duplicate_layout, child);
 
 	WM_check(C);
 
@@ -473,56 +475,67 @@ void wm_window_close(bContext *C, wmWindowManager *wm, wmWindow *win)
 {
 	wmWindow *tmpwin;
 
-	/* first check if we have to quit (there are non-temp remaining windows) */
-	for (tmpwin = wm->windows.first; tmpwin; tmpwin = tmpwin->next) {
-		if (tmpwin == win)
-			continue;
-		if (WM_window_is_temp_screen(tmpwin) == false)
-			break;
+	/* first check if we have to quit (there are non-temp and non-child windows remaining) */
+	if (win->parent == NULL) {
+		for (tmpwin = wm->windows.first; tmpwin; tmpwin = tmpwin->next) {
+			if (tmpwin == win)
+				continue;
+			if (tmpwin->parent == NULL)
+				break;
+			if (WM_window_is_temp_screen(tmpwin) == false)
+				break;
+		}
+
+		if (tmpwin == NULL) {
+			wm_quit_with_optional_confirmation_prompt(C, win);
+			return;
+		}
 	}
 
-	if (tmpwin == NULL) {
-		wm_quit_with_optional_confirmation_prompt(C, win);
+	/* close child windows */
+	for (tmpwin = wm->windows.first; tmpwin; tmpwin = tmpwin->next) {
+		if (tmpwin->parent == win) {
+			wm_window_close(C, wm, tmpwin);
+		}
 	}
-	else {
-		bScreen *screen = WM_window_get_active_screen(win);
-		WorkSpace *workspace = WM_window_get_active_workspace(win);
-		WorkSpaceLayout *layout = BKE_workspace_active_layout_get(win->workspace_hook);
 
-		BLI_remlink(&wm->windows, win);
+	bScreen *screen = WM_window_get_active_screen(win);
+	WorkSpace *workspace = WM_window_get_active_workspace(win);
+	WorkSpaceLayout *layout = BKE_workspace_active_layout_get(win->workspace_hook);
 
-		CTX_wm_window_set(C, win);  /* needed by handlers */
-		WM_event_remove_handlers(C, &win->handlers);
-		WM_event_remove_handlers(C, &win->modalhandlers);
+	BLI_remlink(&wm->windows, win);
 
-		/* for regular use this will _never_ be NULL,
-		 * however we may be freeing an improperly initialized window. */
-		if (screen) {
-			ED_screen_exit(C, win, screen);
-		}
+	CTX_wm_window_set(C, win);  /* needed by handlers */
+	WM_event_remove_handlers(C, &win->handlers);
+	WM_event_remove_handlers(C, &win->modalhandlers);
 
-		if (tmpwin) {
-			BLF_batch_reset();
-			gpu_batch_presets_reset();
-			immDeactivate();
-		}
+	/* for regular use this will _never_ be NULL,
+	 * however we may be freeing an improperly initialized window. */
+	if (screen) {
+		ED_screen_exit(C, win, screen);
+	}
 
-		wm_window_free(C, wm, win);
+	if (tmpwin) {
+		BLF_batch_reset();
+		gpu_batch_presets_reset();
+		immDeactivate();
+	}
 
-		/* keep imediatemode active before the next `wm_window_make_drawable` call */
-		if (tmpwin) {
-			GHOST_ActivateWindowDrawingContext(tmpwin->ghostwin);
-			GWN_context_active_set(tmpwin->gwnctx);
-			immActivate();
-		}
+	wm_window_free(C, wm, win);
+
+	/* keep imediatemode active before the next `wm_window_make_drawable` call */
+	if (tmpwin) {
+		GHOST_ActivateWindowDrawingContext(tmpwin->ghostwin);
+		GWN_context_active_set(tmpwin->gwnctx);
+		immActivate();
+	}
 
-		/* if temp screen, delete it after window free (it stops jobs that can access it) */
-		if (screen && screen->temp) {
-			Main *bmain = CTX_data_main(C);
+	/* if temp screen, delete it after window free (it stops jobs that can access it) */
+	if (screen && screen->temp) {
+		Main *bmain = CTX_data_main(C);
 
-			BLI_assert(BKE_workspace_layout_screen_get(layout) == screen);
-			BKE_workspace_layout_remove(bmain, workspace, layout);
-		}
+		BLI_assert(BKE_workspace_layout_screen_get(layout) == screen);
+		BKE_workspace_layout_remove(bmain, workspace, layout);
 	}
 }
 
@@ -809,7 +822,7 @@ void wm_window_ghostwindows_remove_invalid(bContext *C, wmWindowManager *wm)
 wmWindow *WM_window_open(bContext *C, const rcti *rect)
 {
 	wmWindow *win_prev = CTX_wm_window(C);
-	wmWindow *win = wm_window_new(C);
+	wmWindow *win = wm_window_new(C, win_prev);
 
 	win->posx = rect->xmin;
 	win->posy = rect->ymin;
@@ -869,7 +882,7 @@ wmWindow *WM_window_open_temp(bContext *C, int x, int y, int sizex, int sizey, i
 
 	/* add new window? */
 	if (win == NULL) {
-		win = wm_window_new(C);
+		win = wm_window_new(C, win_prev);
 
 		win->posx = rect.xmin;
 		win->posy = rect.ymin;
@@ -887,7 +900,7 @@ wmWindow *WM_window_open_temp(bContext *C, int x, int y, int sizex, int sizey, i
 
 	if (WM_window_get_active_workspace(win) == NULL) {
 		WorkSpace *workspace = WM_window_get_active_workspace(win_prev);
-		WM_window_set_active_workspace(win, workspace);
+		BKE_workspace_active_set(win->workspace_hook, workspace);
 	}
 
 	if (screen == NULL) {
@@ -904,7 +917,7 @@ wmWindow *WM_window_open_temp(bContext *C, int x, int y, int sizex, int sizey, i
 	}
 	/* In case we reuse an already existing temp window (see win lookup above). */
 	else if (WM_window_get_active_scene(win) != scene) {
-		WM_window_change_active_scene(bmain, C, win, scene);
+		WM_window_set_active_scene(bmain, C, win, scene);
 	}
 
 	screen->temp = 1;
@@ -976,17 +989,25 @@ int wm_window_close_exec(bContext *C, wmOperator *UNUSED(op))
 	return OPERATOR_FINISHED;
 }
 
-/* operator callback */
 int wm_window_new_exec(bContext *C, wmOperator *UNUSED(op))
 {
 	wmWindow *win_src = CTX_wm_window(C);
 	bool ok;
 
-	ok = (wm_window_copy_test(C, win_src, true) != NULL);
+	ok = (wm_window_copy_test(C, win_src, true, true) != NULL);
 
 	return ok ? OPERATOR_FINISHED : OPERATOR_CANCELLED;
 }
 
+int wm_window_new_main_exec(bContext *C, wmOperator *UNUSED(op))
+{
+	wmWindow *win_src = CTX_wm_window(C);
+	bool ok;
+
+	ok = (wm_window_copy_test(C, win_src, true, false) != NULL);
+
+	return ok ? OPERATOR_FINISHED : OPERATOR_CANCELLED;
+}
 
 /* fullscreen operator callback */
 int wm_window_fullscreen_toggle_exec(bContext *C, wmOperator *UNUSED(op))
@@ -2103,21 +2124,45 @@ Scene *WM_window_get_active_scene(const wmWindow *win)
 /**
  * \warning Only call outside of area/region loops
  */
-void WM_window_change_active_scene(Main *bmain, bContext *C, wmWindow *win, Scene *scene_new)
+void WM_window_set_active_scene(Main *bmain, bContext *C, wmWindow *win, Scene *scene)
 {
-	const bScreen *screen = WM_window_get_active_screen(win);
-	Scene *scene_old = win->scene;
+	wmWindowManager *wm = CTX_wm_manager(C);
+	wmWindow *win_parent = (win->parent) ? win->parent : win;
 
-	ED_scene_change_update(bmain, C, win, screen, scene_old, scene_new);
+	/* Set scene in parent and its child windows. */
+	ED_screen_scene_change(C, win_parent, scene);
+
+	for (wmWindow *win_child = wm->windows.first; win_child; win_child = win_child->next) {
+		if (win_child->parent == win_parent) {
+			ED_screen_scene_change(C, win_child, scene);
+		}
+	}
+
+	/* Update depsgraph and renderers for scene change. */
+	ViewLayer *view_layer = WM_window_get_active_view_layer(win_parent);
+	ED_scene_change_update(bmain, scene, view_layer);
+
+	/* Complete redraw. */
+	WM_event_add_notifier(C, NC_WINDOW, NULL);
 }
 
 WorkSpace *WM_window_get_active_workspace(const wmWindow *win)
 {
 	return BKE_workspace_active_get(win->workspace_hook);
 }
-void WM_window_set_active_workspace(wmWindow *win, WorkSpace *workspace)
+
+void WM_window_set_active_workspace(bContext *C, wmWindow *win, WorkSpace *workspace)
 {
-	BKE_workspace_active_set(win->workspace_hook, workspace);
+	wmWindowManager *wm = CTX_wm_manager(C);
+	wmWindow *win_parent = (win->parent) ? win->parent : win;
+
+	ED_workspace_change(workspace, C, wm, win);
+
+	for (wmWindow *win_child = wm->windows.first; win_child; win_child = win_child->next) {
+		if (win_child->parent == win_parent) {
+			ED_workspace_change(workspace, C, wm, win_child);
+		}
+	}
 }
 
 WorkSpaceLayout *WM_window_get_active_layout(const wmWindow *win)