I have a simple custom control consisting of wxStaticText and wxTextCtrl in one sizer.

#include "wx/control.h"

class CParamCtrlEx : public wxControl
{
public:
    CParamCtrlEx(void);
    CParamCtrlEx(wxWindow *parent, wxWindowID id = wxID_ANY, float value_act = 0.0, float value_sp = 0.0, int dec_places = 1);
    ~CParamCtrlEx() {};

    bool Create(wxWindow *parent, wxWindowID id);

private:
    wxBoxSizer *sizer_ = nullptr;
    wxStaticText *act_ = nullptr;
    wxTextCtrl *sp_ = nullptr;

    float value_act_ = 0.0;
    float value_sp_ = 0.0;
    int dec_places_ = 1;

private:
    void UpdateDisplay();

CParamCtrlEx::CParamCtrlEx(void)
{
}

CParamCtrlEx::CParamCtrlEx(wxWindow *parent, wxWindowID id, float value_act, float value_sp, int dec_places) :
    value_act_(value_act),
    value_sp_(value_sp),
    dec_places_(dec_places)
{
    this->Create(parent, id);
}

bool CParamCtrlEx::Create(wxWindow *parent, wxWindowID id)
{
    if (!this->wxControl::Create(parent, id, wxDefaultPosition, wxDefaultSize, wxBORDER_NONE))
        return false;

    wxControl::InheritAttributes();

    act_ = new wxStaticText(this, wxID_ANY, wxString::Format("%.*f /", dec_places_, value_act_));
    sp_ = new wxTextCtrl(this, wxID_ANY, wxString::Format("%.*f", dec_places_, value_sp_), wxDefaultPosition, wxSize(50, -1), wxTE_RIGHT);

    sizer_ = new wxBoxSizer(wxHORIZONTAL);
    sizer_->Add(act_, wxSizerFlags(0).Align(wxALIGN_CENTER_VERTICAL).Border(wxRIGHT, 5));
    sizer_->Add(sp_, wxSizerFlags(1).Expand().Border(wxLEFT | wxRIGHT, 0).FixedMinSize());

    this->SetSizer(sizer_);
    this->Layout();

    return true;
}

void CParamCtrlEx::UpdateDisplay()
{
    act_->SetLabel(wxString::Format("%.*f /", dec_places_, value_act_));
    sp_->SetValue(wxString::Format("%.*f", dec_places_, value_sp_));
    Refresh();
}

Everything would be fine, if it weren’t for the fact that my control has for some reason a different background colour than its parent wxPanel. It is somewhat darker.

I tried to use wxTRANSPARENT_WINDOW style when calling this->wxControl::Create(...), but without success.

How do I fix the background colour?