Fix lock selection text on WEB-Page / UserScript

_fix_lockselection-allsites.user.js

// ==UserScript==
// @name         _Fix lock selection text [allsites]
// @version      1.3
// @description  fix blocking selection on all sites
// @author       Vyachesl Vasiliev
// @include      *
// @downloadURL  https://gist.githubusercontent.com/vyach-vasiliev/8dfb5f5b3c22e1fc74da180f00685929/raw
// @updateURL    https://gist.githubusercontent.com/vyach-vasiliev/8dfb5f5b3c22e1fc74da180f00685929/raw
// @copyright    © MIT, 2017, Vyacheslav Vasiliev
// @grant        none
// @run-at document-end
// ==/UserScript==

/*  The MIT License
Copyright (c) 2017 Vyacheslav Vasiliev (vyach.vasiliev\аt\gmail\dоt\com)
Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:
The above copyright notice and this permission notice shall be included in
all copies or substantial portions of the Software.
THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
THE SOFTWARE. */

function bs_set_fix_selection() {
    // setting fix for selection
    window.bs_options = {
        'fix_mode': true,
    };
    document.addEventListener("selectionchange", function() {
        bs_enable_selection();
    });

    document.addEventListener("keydown", function(e) {
        // restoring hotkeys Ctrl+A, Ctrl+C, Ctrl+V
        var key = event.keyCode || event.which;
        if (event.ctrlKey && (key == 'A'.charCodeAt(0) || key == 'C'.charCodeAt(0) || key == 'V'.charCodeAt(0)) && window.bs_options && window.bs_options.fix_mode) {
            e.returnValue = true;
            // bs_enable_selection();
        }

    });
}
function bs_remove_fix_selection() {
    // remove fix for selection
    if (document.selection) {
        delete document.selection.empty;
        delete document.selection.clear;
    }
    delete window.getSelection().removeAllRanges;
    if (window.bs_options) {
        window.bs_options.fix_mode = false;
    }
}
function bs_enable_selection() {
    // the fix
    if (document.selection) {
        document.selection.empty = null;
        document.selection.clear = null;
    } else if (window.getSelection().removeAllRanges) {
        window.getSelection().removeAllRanges = null;
    }
}

bs_set_fix_selection();
// for disable fix write to console bs_remove_fix_selection();