function getSiblingColumn(sColumn) {
			if (iVisibleColumnsCount === 2) {
				return aVisibleColumns.find(function(sNextColumn) {
					return sNextColumn !== sColumn;
				});
			}
			// all three columns are visible
			if (["begin", "end"].indexOf(sColumn) > -1) {
				return "mid";
			}
			// get sibling for 'mid'
			return (oColumnWidths.begin > oColumnWidths.end) ? "begin" : "end";
		}
Applies predefined contraints to the column widths.
Currently checks if the <code>FlexibleColumnLayout.COLUMN_MIN_WIDTH</code>
constraint is satisfied and corrects the width if not satisfied.
@param {Object<string,number>} oColumnWidths the column widths
@param {array} aVisibleColumns the names of the visible columns