Printhost: Make queue window non-modal, fix upload start progress

src/slic3r/GUI/MainFrame.cpp

@@ -376,7 +376,7 @@ void MainFrame::init_menubar()
 
         windowMenu->AppendSeparator();
         append_menu_item(windowMenu, wxID_ANY, L("Print Host Upload Queue"), L("Display the Print Host Upload Queue window"),
-            [this](wxCommandEvent&) { m_printhost_queue_dlg->ShowModal(); }, "arrow_up.png");
+            [this](wxCommandEvent&) { m_printhost_queue_dlg->Show(); }, "arrow_up.png");
     }
 
     // View menu

src/slic3r/Utils/PrintHost.cpp

@@ -213,6 +213,8 @@ void PrintHostJobQueue::priv::perform_job(PrintHostJob the_job)
 {
     if (bg_exit || the_job.empty()) { return; }
 
+    emit_progress(0);   // Indicate the upload is starting
+
     bool success = the_job.printhost->upload(std::move(the_job.upload_data),
         [this](Http::Progress progress, bool &cancel) { this->progress_fn(std::move(progress), cancel); },
         [this](wxString error) {