Trying to implement a game menu with buttons. When button clicked it enters a submenu which is a new panel. It all works but the problems come with sizers. I have also sizers for every panel and at first when I boot up the program the main menus sizer works – when the window size is changed the maximum size is the sizes of buttons. Now when I go to a submenu, the sizers stop functioning and also when going back to main menu, it doesn’t work there either. What am I doing wrong?

I tried passing

this

into other panel SetSizeHints(), but it turned out it becomes NULL at some point. So I tried passing the panels themselves, but it doesn’t work aswell. My code:

#include "MainFrame.h"
#include "Stats.h"
#include <cstring>
#include <wx/wx.h>
#include "FileAlgo.h"
#include <string>

char sym;


MainFrame::MainFrame(const wxString& title) : wxFrame(nullptr, wxID_ANY, title), main_panel(nullptr), stats_panel(nullptr), game_panel(nullptr) {
    main_panel = new wxPanel(this);
    wxButton* button_start = new wxButton(main_panel, wxID_ANY, "1. Start", wxPoint(325, 150), wxSize(100, 35));
    wxButton* button_stats = new wxButton(main_panel, wxID_ANY, "2. Stats", wxPoint(325, 250), wxSize(100, 35));
    wxButton* button_exit = new wxButton(main_panel, wxID_ANY, "3. Exit", wxPoint(325, 350), wxSize(100, 35));
    
    wxBoxSizer* boxSizer = new wxBoxSizer(wxVERTICAL);
    wxSizerFlags flags = wxSizerFlags().CenterHorizontal().Border(wxALL, 25);

    
    boxSizer->AddStretchSpacer(1);
    boxSizer->Add(button_start, flags);
    boxSizer->Add(button_stats, flags);
    boxSizer->Add(button_exit, flags);
    boxSizer->AddStretchSpacer(1);
    main_panel->SetSizer(boxSizer);
    boxSizer->SetSizeHints(this);

    button_start->Bind(wxEVT_BUTTON, &MainFrame::OnStartClicked, this);
    button_stats->Bind(wxEVT_BUTTON, &MainFrame::OnStatsClicked, this);
    button_exit->Bind(wxEVT_BUTTON, &MainFrame::OnExitClicked, this);
    CreateStatusBar();
    SetClientSize(700, 500);
}

void MainFrame::OnStartClicked(wxCommandEvent& evt) {
    wxLogStatus("Button Clicked1");
    if (!game_panel) {
        //genFile()
        std::vector<std::string> text = readFromFile(genFile());
        //std::string tekst_blokk(text.begin(), text.end());
        /*for (char sym : text) {
            tekst_blokk += sym;
        }*/
        std::string tekst_to_display;
        for (const auto& text_line : text) {
            tekst_to_display += text_line;
        }
        game_panel = new wxPanel(this);
        wxStaticText* game_text = new wxStaticText(game_panel, wxID_ANY, tekst_to_display);
        wxBoxSizer* boxSizerGM = new wxBoxSizer(wxVERTICAL);
        wxSizerFlags flags_gm = wxSizerFlags().CenterHorizontal().Border(wxALL, 25);

        boxSizerGM->AddStretchSpacer(1);
        boxSizerGM->Add(game_text, flags_gm);
        boxSizerGM->AddStretchSpacer(1);
        game_panel->SetSizer(boxSizerGM);
        boxSizerGM->SetSizeHints(game_panel);
    }
    main_panel->Hide();
    game_panel->Show();
    game_panel->SetSize(GetClientSize());
    Layout();
}
void MainFrame::OnExitStatsClicked(wxCommandEvent& evt) {
    stats_panel->Hide();
    main_panel->Show();
}

void MainFrame::OnStatsClicked(wxCommandEvent& evt) {
    wxLogStatus("Button Clicked2");
    if (!stats_panel) {
        Stats gameStats;
        stats_panel = new wxPanel(this);

        wxButton* button_exit_st = new wxButton(stats_panel, wxID_ANY, "Peamenüü", wxPoint(325, 250), wxSize(100, 35));
        std::vector<std::string> lastTenLines = gameStats.getLastTenLines();
        std::string statistika{};
        for (const auto& line : lastTenLines) {
            statistika += line + 'n';
        }
        //wxLogStatus(statistika);
        wxStaticText* stat_box = new wxStaticText(stats_panel, wxID_ANY, statistika);

        wxBoxSizer* boxSizerST = new wxBoxSizer(wxVERTICAL);
        wxSizerFlags flags_st = wxSizerFlags().CenterHorizontal().Border(wxALL, 25);

        boxSizerST->AddStretchSpacer(1);
        boxSizerST->Add(stat_box, flags_st);
        boxSizerST->Add(button_exit_st, flags_st);
        boxSizerST->AddStretchSpacer(1);
        stats_panel->SetSizer(boxSizerST);
        boxSizerST->SetSizeHints(stats_panel);
        button_exit_st->Bind(wxEVT_BUTTON, &MainFrame::OnExitStatsClicked, this);
    }
    main_panel->Hide();
    stats_panel->Show();
    stats_panel->SetSize(GetClientSize());
    Layout();
    
    }
void MainFrame::OnExitClicked(wxCommandEvent& evt) {
    wxLogStatus("Éxiting");
    Close(true);
}