Merge pull request #37 from d-j-a-y/master

Fix - Add Keyframe crash
get_window hunt - dialog setup
get_window initial test / window variable usage
get_window hunt - sound widget
get_window initial test (remplacement) / window variable usage
get_window hunt - gradient widget
get_window initial test (remplacement) / window variable usage
get_window hunt - curves widget
get_window initial test / window variable usage
get_window hunt - default widget (brush widget)
get_window initial test / window variable usage
get_window hunt - coloredit widget (ColorSlider)
get_window initial test / window variable usage
get_window hunt - color widget
get_window initial test / window variable usage
get_window hunt - preview dialog
get_window initial test / window variable usage
get_window hunt - workarea
get_window initial test / window variable usage
get_window hunt - preview dialog FIX
in all case we need to set_preview!