message: Fix HiDPI +/- buttons in properties on Windows
  Fix size to respect HiDPI scaling, instead of being tiny, and also
  slightly adjust spacing around the buttons to look better.
diff: @@ -270,22 +270,26 @@ public:
  auto lbl = new wxStaticText(this, wxID_ANY, label);
  sizer->Add(lbl, wxSizerFlags().Expand());
  m_list = new wxListBox(this, wxID_ANY, wxDefaultPosition, wxDefaultSize, 0, nullptr, wxLB_EXTENDED);
  - sizer->Add(m_list, wxSizerFlags(1).Expand());
  + sizer->Add(m_list, wxSizerFlags(1).Expand().BORDER_WIN(wxLEFT, 1));
  #if defined(__WXOSX__)
  auto add = new wxBitmapButton(this, wxID_ANY, wxArtProvider::GetBitmap("NSAddTemplate"), wxDefaultPosition, wxSize(18, 18), wxBORDER_SUNKEN);
  auto remove = new wxBitmapButton(this, wxID_ANY, wxArtProvider::GetBitmap("NSRemoveTemplate"), wxDefaultPosition, wxSize(18,18), wxBORDER_SUNKEN);
  #elif defined(__WXMSW__)
  - auto add = new wxBitmapButton(this, wxID_ANY, wxArtProvider::GetBitmap("list-add"), wxDefaultPosition, wxSize(19,19));
  - auto remove = new wxBitmapButton(this, wxID_ANY, wxArtProvider::GetBitmap("list-remove"), wxDefaultPosition, wxSize(19,19));
  + auto add = new wxBitmapButton(this, wxID_ANY, wxArtProvider::GetBitmap("list-add"), wxDefaultPosition, wxSize(PX(19),PX(19)));
  + auto remove = new wxBitmapButton(this, wxID_ANY, wxArtProvider::GetBitmap("list-remove"), wxDefaultPosition, wxSize(PX(19),PX(19)));
  #elif defined(__WXGTK__)
  auto add = new wxBitmapButton(this, wxID_ANY, wxArtProvider::GetBitmap("list-add"), wxDefaultPosition, wxDefaultSize, wxNO_BORDER);
  auto remove = new wxBitmapButton(this, wxID_ANY, wxArtProvider::GetBitmap("list-remove"), wxDefaultPosition, wxDefaultSize, wxNO_BORDER);
  #endif
  auto buttonSizer = new wxBoxSizer(wxHORIZONTAL);
  buttonSizer->Add(add);
  +#ifdef __WXOSX__
  + buttonSizer->AddSpacer(PX(1));
  +#endif
  buttonSizer->Add(remove);
  - sizer->Add(buttonSizer);
  + sizer->AddSpacer(PX(1));
  + sizer->Add(buttonSizer, wxSizerFlags().BORDER_MACOS(wxLEFT, PX(1)));
  SetDropTarget(new DropTarget(this));
  