Fixed crash with new thread-safety code (primarily on watermarks)

Actually added only showing "open recent set" if exists
Removed a call to deprecated functions.

src/gui/value/choice.cpp

@@ -41,9 +41,9 @@ ChoiceThumbnailRequest::ChoiceThumbnailRequest(ValueViewer* cve, int id, bool fr
 	, stylesheet(cve->viewer.stylesheet)
 	, id(id)
 {
-	ChoiceValueEditor& e = *(ChoiceValueEditor*)cve;
+	ChoiceValueEditor e = *(ChoiceValueEditor*)cve;
 	String name = cannocial_name_form(e.field().choices->choiceName(id));
-	ScriptableImage& img = e.style().choice_images[name];
+	ScriptableImage img = e.style().choice_images[name];
 	isThreadSafe = img.threadSafe();
 }
 

src/gui/welcome_window.cpp

@@ -39,11 +39,12 @@ WelcomeWindow::WelcomeWindow()
 	wxControl* open_last = nullptr;
 	if (!settings.recent_sets.empty()) {
 		wxFileName n(settings.recent_sets.front());
-		#ifdef USE_HOVERBUTTON
-			open_last       = new HoverButtonExt(this, ID_FILE_RECENT, load_resource_image(_("welcome_last")), _BUTTON_("last opened set"), _("Open '") + n.GetName() + _("'"));
-		#else
-			open_last       = new wxButton(this, ID_FILE_RECENT, _BUTTON_("last opened set"));
-		#endif
+		if (n.FileExists())
+			#ifdef USE_HOVERBUTTON
+				open_last       = new HoverButtonExt(this, ID_FILE_RECENT, load_resource_image(_("welcome_last")), _BUTTON_("last opened set"), _("Open '") + n.GetName() + _("'"));
+			#else
+				open_last       = new wxButton(this, ID_FILE_RECENT, _BUTTON_("last opened set"));
+			#endif
 	}
 	
 	wxSizer* s1  = new wxBoxSizer(wxHORIZONTAL);
@@ -60,10 +61,9 @@ WelcomeWindow::WelcomeWindow()
 
 void WelcomeWindow::onPaint(wxPaintEvent&) {
 	wxBufferedPaintDC dc(this);
-	dc.BeginDrawing();
 	draw(dc);
-	dc.EndDrawing();
 }
+
 void WelcomeWindow::draw(DC& dc) {
 	wxSize ws = GetClientSize();
 	// draw background

src/script/image.hpp

@@ -47,7 +47,7 @@ class ScriptableImage {
 	}
 
 	/// Can this be safely generated from another thread?
-	bool threadSafe() const {return value->threadSafe();}
+	bool threadSafe() const {return value != nullptr ? value->threadSafe() : false; }
 	
   private:
 	OptionalScript  script;		///< The script, not really optional