Misc. ramblings from my notes:

• IDEA: have the pane call some method on it's child controls to have it indroduce some margin, as opposed to creating some manual seperator. When the control is focused, colorize the margin. When it's unfocused, remove that color. Each pane optionally tells a control should it have margin on top/bottom/left/right, and does it recursively? so

[A|B]
A should have a right margin, b should have a left.

[A|[B-C]]
A has right
B has left, bottom
C has left, top

[A|[[B-D]-C]]
A has right
B has left, bottom(with D), bottom(with C)
C has left, top(with B-D)
D has left, top(with B), bottom(with C)

Margin doesn't stack, just is there or isn't
Margin color should be either null, accent, or a color (Global, Control)
Margin should have configurable width (Global, Control)

How does this interact with #992? Can we detect a click is in the margin, and surface that up? or can the terminal app listen to the control's click/drag, and handle it somehow?