refactoring event define
implement popup view (perhaps need refactoring view hierarchy)
implement cheap command line suggestion and complement mechanism.
replace moving channel change and reading song procedure with new one.
replacing is in progress.
migrate velocity command
migrate tempo command and fix regix
shorten operation enum name
fix arguments mistake
migrate beat command
implement cheap filename suggestion and auto complete
migrate write command
better filename completion
migrate commands. copy, move, erase, delete and insert
exchange 'to' and 'length' params from copy and move commands
quit from command line