@Override
	public void setColumnMargin(int newMargin) {
		if (newMargin != columnMargin) {
			columnMargin = newMargin;
			// Post columnMarginChanged event notification.
			fireColumnMarginChanged();
		}
	}
This returns all columns known by this model, both visible and not seen.
@return all columns known by this model, both visible and not seen.
Ghidra/Framework/Docking/src/main/java/docking/widgets/table/GTableColumnModel.java