Add instrument mixing throughout songs.

Basically, it's the mixer bar, but there's a way to make it change as the song plays. Maybe there's a pencil icon next to a setting (volume or channel) and it allows you to draw the setting on the music which changes up and down throughout notes and measure.

Let's use an example: You click the pencil icon on "volume" and draw a line going left to right in the music, and you're able to move the line up and down, the higher the line is, the higher the volume, the lower the setting, the lower the volume. This is perfect for changing who's playing a melody in music when all the dynamics are the same.

Another example: You click on the pencil icon for "channel" and draw a line left to right across the music, and you're able to move it up and down, and there's 3 guide-lines, the middle line shows that the instrument is perfectly in the middle, the top one shows that the instrument is on the right, the left one shows that the instruments is on the left. This is good for making music that has sweeping instruments through the ears, which previously could only be done by making multiple instruments for this purpose, which does not sound good.

Once you're done drawing the lines, they become invisible, and can only be seen by clicking on the slider bar for each setting, and can only be edited by clicking the pencil icon again.

Also, these lines will change the setting in the middle of notes if you want, so you can have, for example, a trumpet playing a whole note and while it's being played it sweeps from the right to left.