fix save dialogs on Mac #268

In MainFrame::ShowModal, which is used as a wrapper for
wxDialog::ShowModal to also pause emulation, add the current window
style flags to the additional CAPTION and RESIZE_BORDER flags being set
with SetWindowStyle(), otherwise the other style flags of the window are
reset causing erroneous behavior such as save dialogs appearing as open
dialogs on Mac.

src/wx/wxvbam.cpp

@@ -896,7 +896,7 @@ void MainFrame::SetMenusOpened(bool state)
 // uses dialog_opened as a nesting counter
 int MainFrame::ShowModal(wxDialog* dlg)
 {
-    dlg->SetWindowStyle(wxCAPTION | wxRESIZE_BORDER);
+    dlg->SetWindowStyle(dlg->GetWindowStyle() | wxCAPTION | wxRESIZE_BORDER);
 
     if (gopts.keep_on_top)
         dlg->SetWindowStyle(dlg->GetWindowStyle() | wxSTAY_ON_TOP);