input: tweak focus behavior to allow focusing parent containers

Sway focuses the inactive child when focusing split containers. However,
there is currently no way to focus the parent container itself by mouse.
A user must use the keyboard to do so.

This commit maintains the current behavior, but makes it such that a
second click on the split container titlebar (i.e., after its children
are visible) focuses the split container itself.

sway/input/seatop_default.c

@@ -429,13 +429,31 @@ static void handle_button(struct sway_seat *seat, uint32_t time_msec,
 		}
 	}
 
+	// Handle changing focus when clicking on a container
+	if (cont && state == WLR_BUTTON_PRESSED) {
+		// Default case: focus the container that was just clicked.
+		node = &cont->node;
+
+		// If the container is a tab/stacked container and the click happened
+		// on a tab, switch to the tab. If the tab contents were already
+		// focused, focus the tab container itself. If the tab container was
+		// already focused, cycle back to focusing the tab contents.
+		if (on_titlebar) {
+			struct sway_container *focus = seat_get_focused_container(seat);
+			if (focus == cont || !container_has_ancestor(focus, cont)) {
+				node = seat_get_focus_inactive(seat, &cont->node);
+			}
+		}
+
+		seat_set_focus(seat, node);
+		transaction_commit_dirty();
+	}
+
 	// Handle beginning floating move
 	if (cont && is_floating_or_child && !is_fullscreen_or_child &&
 			state == WLR_BUTTON_PRESSED) {
 		uint32_t btn_move = config->floating_mod_inverse ? BTN_RIGHT : BTN_LEFT;
 		if (button == btn_move && (mod_pressed || on_titlebar)) {
-			seat_set_focus_container(seat,
-					seat_get_focus_inactive_view(seat, &cont->node));
 			seatop_begin_move_floating(seat, container_toplevel_ancestor(cont));
 			return;
 		}
@@ -471,25 +489,18 @@ static void handle_button(struct sway_seat *seat, uint32_t time_msec,
 	if (config->tiling_drag && (mod_pressed || on_titlebar) &&
 			state == WLR_BUTTON_PRESSED && !is_floating_or_child &&
 			cont && cont->pending.fullscreen_mode == FULLSCREEN_NONE) {
-		struct sway_container *focus = seat_get_focused_container(seat);
-		bool focused = focus == cont || container_has_ancestor(focus, cont);
-		if (on_titlebar && !focused) {
-			node = seat_get_focus_inactive(seat, &cont->node);
-			seat_set_focus(seat, node);
-		}
-
 		// If moving a container by its title bar, use a threshold for the drag
 		if (!mod_pressed && config->tiling_drag_threshold > 0) {
 			seatop_begin_move_tiling_threshold(seat, cont);
 		} else {
 			seatop_begin_move_tiling(seat, cont);
 		}
+
 		return;
 	}
 
 	// Handle mousedown on a container surface
 	if (surface && cont && state == WLR_BUTTON_PRESSED) {
-		seat_set_focus_container(seat, cont);
 		seatop_begin_down(seat, cont, time_msec, sx, sy);
 		seat_pointer_notify_button(seat, time_msec, button, WLR_BUTTON_PRESSED);
 		return;
@@ -497,9 +508,6 @@ static void handle_button(struct sway_seat *seat, uint32_t time_msec,
 
 	// Handle clicking a container surface or decorations
 	if (cont && state == WLR_BUTTON_PRESSED) {
-		node = seat_get_focus_inactive(seat, &cont->node);
-		seat_set_focus(seat, node);
-		transaction_commit_dirty();
 		seat_pointer_notify_button(seat, time_msec, button, state);
 		return;
 	}