window: Clear resize_cursor on leave notify events (!6090) · Merge requests · GNOME / gtk · GitLab
gitlab.gnome.org
When the pointer leaves the window surface, gtk_window_capture_motion will not be called anymore, so priv->resize_cursor may remain non-NULL indefinitely without this. If update_cursor is later called...

The issue in the link already has a proposed solution (as far as I understand), but I don’t understand how I can “use” that. Can I just copy-pasta the code? Or is it more complicated?