h file:

#ifndef CONTROLMENUCLASS_H
#define CONTROLMENUCLASS_H

#include <QMainWindow>
#include <QJsonObject>
#include <QThread>
#include <QTimer>

#include <QScreen>

class ApiFunctionsClass;
class CustomWidgetClass;
class ProcessesControllerClass;

QT_BEGIN_NAMESPACE
namespace Ui { class control_menu_ui; }
QT_END_NAMESPACE

class ControlMenuClass : public QMainWindow
{
    Q_OBJECT

public:
    ControlMenuClass(QString json_params_path_param, QWidget *parent = nullptr);
    ~ControlMenuClass();

private:
    QString json_params_path;
    QJsonObject ui_params;
    bool event_flag = false;

    ApiFunctionsClass *api = nullptr;
    CustomWidgetClass *custom_widget = nullptr;
    ProcessesControllerClass *worker = nullptr;

    QTimer *timer = nullptr;

    void program_launch();
    void exit_program(int status_code);

protected:
    bool eventFilter(QObject *, QEvent *event);

private slots:
    void timer_slot();
    void program_stop_slot();
    void show_message_slot(QString text);

private:
    Ui::control_menu_ui *ui;
};
#endif // CONTROLMENUCLASS_H


-------------------------------------------------------------------------------
cpp file:

ControlMenuClass::ControlMenuClass(QString json_params_path_param, QWidget *parent) : QMainWindow(parent), json_params_path(json_params_path_param), ui(new Ui::control_menu_ui){
    this->move(0,0);
//    QCoreApplication::instance()->installEventFilter(this);
    this->installEventFilter(this);

    ui->setupUi(this);
    this->setWindowModality(Qt::ApplicationModal);

    qobject_cast<QMainWindow*>(this)->setWindowFlags(Qt::Window | Qt::FramelessWindowHint);
    qobject_cast<QMainWindow*>(this)->centralWidget()->setStyleSheet("QWidget#centralWidget{border-style: solid; border-width: 3px; border-color: #cc5d44;}");

    api = new ApiFunctionsClass(this);
    api->load_registry_settings("bilbo_project/control_menu");

    custom_widget = new CustomWidgetClass(this);

    program_launch();
}

ControlMenuClass::~ControlMenuClass(){
    api->save_registry_settings("bilbo_project/control_menu");

    delete ui;
}

bool ControlMenuClass::eventFilter(QObject *, QEvent *event){
    if ( event->type() == event->Hide && !event_flag ) { qDebug() << 1; event->accept(); return true; }//this->show(); }
    if ( event->type() == event->Resize && !event_flag ) { qDebug() << 1; event->accept(); return true; }

    return false;
}



//--------------------------------------------------------GUI FUNCTIONS-----------------------------------------------------------------//

void ControlMenuClass::program_launch(){
    api->save_registry_settings("bilbo_project/control_menu");

    QString ui_params_str = api->get_file_data(json_params_path);
    ui_params = QJsonDocument::fromJson(ui_params_str.toUtf8()).object();

    if ( !ui_params.contains("threads_count") ) { return exit_program(-1); }

    if ( !ui_params.contains("sphere_file_line") ) { return exit_program(-2); }
    if ( !ui_params.contains("ls_login") ) { return exit_program(-3); }

    if ( !ui_params.contains("proxy_dir_line") ) { return exit_program(-4); }
    if ( !ui_params.contains("port_range_min") ) { return exit_program(-5); }
    if ( !ui_params.contains("port_range_max") ) { return exit_program(-6); }

    if ( !ui_params.contains("logs_dir_line") ) { return exit_program(-7); }
    if ( !ui_params.contains("work_dir_line") ) { return exit_program(-8); }

    if ( !ui_params.contains("sites_number") ) { return exit_program(-9); }
    if ( !ui_params.contains("deep") ) { return exit_program(-10); }
    if ( !ui_params.contains("pages_time") ) { return exit_program(-11); }

    if ( !ui_params.contains("sites_keywords") ) { ui_params["sites_keywords"] = ""; }
    if ( !ui_params.contains("current_blacklist") ) { ui_params["current_blacklist"] = QJsonArray(); }

    ui_params["blacklist"] = true;
    ui_params["filter"] = false;
    ui_params["keywords_number"] = 0;
    ui_params["mode_keywords"] = false;
    ui_params["mode_sites"] = true;

    timer = new QTimer;
    timer->setSingleShot(true);
    connect(timer, SIGNAL(timeout()), this, SLOT(timer_slot()));
    timer->start(1000);
}

void ControlMenuClass::program_stop_slot(){ worker->thread_control_flag = false; }

void ControlMenuClass::timer_slot(){
    if ( timer ) { timer->deleteLater(); timer = nullptr; }

    this->resize(200, 300);
    this->hide();

//    QThread* thread = new QThread;
//    worker = new ProcessesControllerClass(this, ui_params, custom_widget, static_cast<int>(custom_widget->winId()));
//    worker->moveToThread(thread);
//    connect(thread, SIGNAL(started()), worker, SLOT(process()));
//    connect(worker, SIGNAL(finished()), thread, SLOT(quit()));
//    connect(worker, SIGNAL(finished()), worker, SLOT(deleteLater()));
//    connect(thread, SIGNAL(finished()), thread, SLOT(deleteLater()));

//    thread->start();
}

void ControlMenuClass::show_message_slot(QString text){ qDebug() << text; }

void ControlMenuClass::exit_program(int status_code){ qDebug() << status_code; }