Follow the other answer (one main horizontal splitter and two vertical splitters inside each of the panels, to give you the 4 separate panels).
Then hook up one of the vertical SplitContainer's SplitterMoved events (there may be reasons to use SplitterMoving, I'm not 100% on that. I'd go with SplitterMoved).
Inside the handler for that event, set the OTHER vertical splitter.SplitterDistance to be the first vertical splitter.SplitterDistance.
You should then be able to have all 4 panels stay in sync.