Fix crash on close patch rebased for stable
Merge pull request #570 from diizy/stable-1.0

Fix crash on close patch rebased for stable
corrects the drag'n'drop behavior in the song editor.
Merge pull request #574 from BaraMGB/songeditor

corrects the drag'n'drop behavior in the song editor.
Fix broken command line rendering. Should always check that editor windows exist before using them.