function addSelListener(node) {
    if (!node || "cbSelListener" in node) return;
    var sl = {
        node: node,
        win: null,
        winSel: null,
        lastSel: "",
        hasSel: false,
        mouseDown: false,

        init: function() {
            this.win = this.node.ownerDocument.defaultView;
            this.winSel = this.win.getSelection().QueryInterface(Ci.nsISelectionPrivate);
            this.hasSel = this.winSel.containsNode(this.node, true);

            this.node.cbSelListener = true;
            this.winSel.addSelectionListener(this);
            this.addListeners(true);
        },
        destroy: function() {
            if (!this.node) return;
            delete this.node.cbSelListener;
            this.winSel.removeSelectionListener(this);
        },
        addListeners: function(add) {
            var sl = this;
            var func = add ? addEventListener : removeEventListener;
            ["unload", "mousedown", "mouseup", "blur"].forEach(function(type)
                func(type, sl, false, sl.win)
            );
        },
        handleEvent: function(e) {
            if (e instanceof MouseEvent && e.button) return;
            this[e.type](e);
        },
        unload: function(e) {
            this.addListeners(false);
            this.destroy();
            this.node = null;
        },
        mousedown: function() this.mouseDown = true,
        mouseup: function() this.mouseDown = false,
        blur: function() this.mouseDown = false,

        notifySelectionChanged: function(doc, sel, reason) {
            if (this.mouseDown) return;
            if (sel.isCollapsed || !sel.containsNode(this.node, true)) {
                if (this.hasSel) {
                    this.hasSel = false;
                    this.onUnselect();
                }
                return;
            }
            this.hasSel = true;

            var str = "";
            var nodeRange = doc.createRange();
            nodeRange.selectNode(this.node);

            for(var r = 0; r < sel.rangeCount; r++) {
                var range = sel.getRangeAt(r).cloneRange();

                var [nodeStartsAfter, nodeEndsBefore, nodeStartsBefore, nodeEndsAfter] =
                    "END_TO_START START_TO_END START_TO_START END_TO_END".split(" ")
                    .map(function(how) range.compareBoundaryPoints(Range[how], nodeRange)
                        == (how[0] == "E" ? 1 : -1)
                    );
                if (nodeStartsAfter || nodeEndsBefore) continue;
                if (nodeStartsBefore) range.setStart(this.node, 0);
                if (nodeEndsAfter) range.setEnd(nodeRange.endContainer, nodeRange.endOffset);
        
                str += range.toString();
            }
            if (this.lastSel == str) return;
            this.lastSel = str;
            this.onSelect(str);
        },
        onSelect: function(txt) {

            Services.console.logStringMessage(_id + " - SELECT:\n" + txt);
            custombuttons.alertBox(_id, "SELECT:\n" + txt);
        },
        onUnselect: function() {

            Services.console.logStringMessage(_id + " - UNSELECT");
            custombuttons.alertBox(_id, "UNSELECT");
        }
    };
    sl.init();
    addDestructor(sl.destroy, sl);
}