Is working in a mixed-gender room with women, with the door left open, considered unlawful seclusion (khalwa), and does keeping the door open prevent it from being (unlawful) seclusion?

Unlawful seclusion (khalwa (definition)) is the gathering of two non-mahram (definition) individuals in a place where there is no assurance that a third person will enter upon them. If the door is open or there is a gathering of women, it prevents it from being unlawful seclusion. Unlawful mixing (ikhtilat) must be avoided. Mixing becomes unlawful if it involves seclusion with a non-mahram woman, or looking with lust, or the woman's immodest display and lack of proper covering, or frivolous play and physical contact.