Fix multi widget render window access
Fix multi widget render window access

fmilano/mitk,MITK/MITK,MITK/MITK,MITK/MITK,fmilano/mitk,MITK/MITK,fmilano/mitk,MITK/MITK,fmilano/mitk,MITK/MITK,fmilano/mitk,fmilano/mitk,fmilano/mitk