int move( int from, int to );
int resize_clip( int clip, int in, int out );
int split( int clip, int position );
+ int split_at( int position, bool left = true );
int join( int clip, int count = 1, int merge = 1 );
int mix( int clip, int length, Transition *transition = NULL );
int mix_add( int clip, Transition *transition );