Fix usage of CallAfter vs modal dialogs in slic3r.cpp, fix #1778

src/slic3r.cpp

@@ -131,6 +131,9 @@ int main(int argc, char **argv)
         GUI::GUI_App *gui = new GUI::GUI_App();
         GUI::GUI_App::SetInstance(gui);
         gui->CallAfter([gui, &input_files, &cli_config, &extra_config, &print_config] {
+            if (! gui->initialized()) {
+                return;
+            }
 #if 0
             // Load the cummulative config over the currently active profiles.
             //FIXME if multiple configs are loaded, only the last one will have an effect.

src/slic3r/GUI/GUI_App.cpp

@@ -197,7 +197,7 @@ bool GUI_App::OnInit()
 
 
     mainframe->Show(true);
-    return true;
+    return m_initialized = true;
 }
 
 unsigned GUI_App::get_colour_approx_luma(const wxColour &colour)

src/slic3r/GUI/GUI_App.hpp

@@ -71,6 +71,7 @@ static wxString dots("…", wxConvUTF8);
 
 class GUI_App : public wxApp
 {
+    bool            m_initialized { false };
     bool            app_conf_exists{ false };
 
     wxColour        m_color_label_modified;
@@ -90,6 +91,7 @@ class GUI_App : public wxApp
 
 public:
     bool            OnInit() override;
+    bool            initialized() const { return m_initialized; }
 
     GUI_App();