window: Add support for the blank cursor

clients/window.c

@@ -2398,6 +2398,12 @@ pointer_surface_frame_callback(void *data, struct wl_callback *callback,
 		input->cursor_frame_cb = NULL;
 	}
 
+	if (input->current_cursor == CURSOR_BLANK) {
+		wl_pointer_set_cursor(input->pointer, input->display->serial,
+				      NULL, 0, 0);
+		return;
+	}
+
 	if (input->current_cursor == CURSOR_UNSET)
 		return;
 	cursor = input->display->cursors[input->current_cursor];

clients/window.h

@@ -153,7 +153,9 @@ enum cursor_type {
 	CURSOR_TOP,
 	CURSOR_IBEAM,
 	CURSOR_HAND1,
-	CURSOR_WATCH
+	CURSOR_WATCH,
+
+	CURSOR_BLANK
 };
 
 typedef void (*window_key_handler_t)(struct window *window, struct input *input,