In the pattern editor, channel width is set by the "lo/med/hi" buttons.
I'd like to set the width of each channel independently
by dragging vertical separators (or by another mean).
The width would snap to the lo/med/hi levels of display.
: The dragging area would be limited to the label box (the mouse would turn into 'vspilt' when hovering over separators) to avoid confusion when editing the pattern with the mouse.