Added beforeClose handler to Streams/preview base tool
Added beforeClose handler to Streams/preview base tool

EGreg/Platform,casualuser/Qbix,jkokh/Platform,EGreg/Platform,Qbix/Platform,jkokh/Platform,jkokh/Platform,EGreg/Platform,Qbix/Platform,Qbix/Platform,Qbix/Platform,AndreyTepaykin/Platform,casualuser/Qbix,casualuser/Qbix,AndreyTepaykin/Platform,AndreyTepaykin/Platform,jkokh/Platform,EGreg/Platform,AndreyTepaykin/Platform,casualuser/Qbix