function _selEq(sel1, sel2) {
        return (CodeMirror.cmpPos(sel1.start, sel2.start) === 0 && CodeMirror.cmpPos(sel1.end, sel2.end) === 0);
    }
@private
Helper function. Returns true if two selections are equal.
@param {!{start: {line: number, ch: number}, end: {line: number, ch: number}}} sel1 The first selection to compare
@param {!{start: {line: number, ch: number}, end: {line: number, ch: number}}} sel2 The second selection to compare
@return {boolean} true if the selections are equal