Fix of #6650 - show estimated print time on ruler is not working

+ Parent center of the MessageDialogs

src/slic3r/GUI/MsgDialog.cpp

@@ -32,6 +32,7 @@ MsgDialog::MsgDialog(wxWindow *parent, const wxString &title, const wxString &he
 	boldfont.SetWeight(wxFONTWEIGHT_BOLD);
 
     this->SetFont(wxGetApp().normal_font());
+    this->CenterOnParent();
 
 	auto *topsizer = new wxBoxSizer(wxHORIZONTAL);
 	auto *rightsizer = new wxBoxSizer(wxVERTICAL);