Your interface:

Thanks to Martyn for this interface idea:


The top section contains the main transport controlls, the bar number, tempo and volume.
Below that are 4 tabs that contain 4 identical synths, the only difference is the highlight colour.
Below the tabs is a section representing the 16 steps of a bar and an indication of whether the step contains any note. The arrows can be used to step forward or back. The small arrow shows the current step. Each step can contain up to four notes.
Notes can be entered using the keyboard along the bottom. The bar above can be used to move up and down the keyboard.
The four slide controls above the keyboard are attack, decay, sustain and release. The other four slide controls are filter, resonance, delay and distort (possibly)
In the center is a pattern selector. A pattern contains all 16 steps.
When record is enabled, all pattern changes and changes to the slide controls are recorded.
The arrows to the left are used to import or export track, possibly containing other settings.

It looks like a really interesting interface. Any takers to make it a reality?