Possible fix for bug 584:

Don't compress note data in the editor.

I need confirmation that this works as intended before
it goes into the changelog and whatnot.

src/Steps.cpp

@@ -380,6 +380,12 @@ void Steps::Compress() const
 		return;
 	}
 	
+	// Don't compress data in the editor: it's still in use.
+	if (GAMESTATE->m_bInStepEditor)
+	{
+		return;
+	}
+
 	if( !m_sFilename.empty() && m_LoadedFromProfile == ProfileSlot_Invalid )
 	{
 		/* We have a file on disk; clear all data in memory.