gui: improve RichMessageDialog (#5371)

* gui: improve RichMessageDialog

Current implementation of RichMessageDialog creates and pushes
extra checkbox widget into button button sizer which already filled in
with wxEXPAND items. That pushes position of newly added checkbox to the
left-most position which makes it invisibe for some users.

Optimize implementation of RichMessageDialog using m_checkbox_dsa of
MessageDialog instead of creating a new one. As a result, position of
the checkbox is right below the main text section.

src/slic3r/GUI/MsgDialog.cpp

@@ -383,26 +383,27 @@ RichMessageDialog::RichMessageDialog(wxWindow* parent,
     : MsgDialog(parent, caption.IsEmpty() ? wxString::Format(_L("%s info"), SLIC3R_APP_FULL_NAME) : caption, wxEmptyString, style)
 {
     add_msg_content(this, content_sizer, message);
-
-    m_checkBox = new wxCheckBox(this, wxID_ANY, m_checkBoxText);
-    wxGetApp().UpdateDarkUI(m_checkBox);
-    m_checkBox->Bind(wxEVT_CHECKBOX, [this](wxCommandEvent&) { m_checkBoxValue = m_checkBox->GetValue(); });
-
-    btn_sizer->Insert(0, m_checkBox, wxALIGN_CENTER_VERTICAL);
-
     finalize();
 }
 
 int RichMessageDialog::ShowModal()
 {
-    if (m_checkBoxText.IsEmpty())
-        m_checkBox->Hide();
-    else
-        m_checkBox->SetLabelText(m_checkBoxText);
+    if (!m_checkBoxText.IsEmpty()) {
+        show_dsa_button(m_checkBoxText);
+        m_checkbox_dsa->SetValue(m_checkBoxValue);
+    }
     Layout();
 
     return wxDialog::ShowModal();
 }
+
+bool RichMessageDialog::IsCheckBoxChecked() const
+{
+    if (m_checkbox_dsa)
+        return m_checkbox_dsa->GetValue();
+
+    return m_checkBoxValue;
+}
 #endif
 
 // InfoDialog