Never heard that oblok/oblak in Russian means "window" :)
"Cloud" in Russian is "oblako" - the same as in Serbian, and "window" in Russian is "okno".
:)

>The trouble with Serbian vs Russian is with false friends. Since the languages share a common root, there are many words which are recognized as common, while they have different meanings. Here's a few common triplets:
>
>

>word          meaning (ru)       meaning (sr)
>krasni        red                nice
>pravo         right              straight
>oblok/oblak   window             cloud
>slovo         word               letter, character
>rech          speech             word
>pitat'        feed               ask (a question)
>iskustvo      art                experience