make active model chooser change visiility (less confusing?)

Fltk/Main.cpp

@@ -81,8 +81,10 @@ int main(int argc, char *argv[])
   // Open project file and merge all other input files
   OpenProject(CTX.filename);
   for(unsigned int i = 1; i < CTX.files.size(); i++){
-    if(CTX.files[i] == "-new")
+    if(CTX.files[i] == "-new"){
+      GModel::current()->setVisibility(0);
       new GModel();
+    }
     else
       MergeFile(CTX.files[i].c_str());
   }

Fltk/extraDialogs.cpp

@@ -142,7 +142,11 @@ int perspective_editor()
 static void model_switch_cb(Fl_Widget* w, void *data)
 {
   Fl_Select_Browser *b = (Fl_Select_Browser *)w;
-  if(b->value()) GModel::current(b->value() - 1);
+  if(b->value()){
+    GModel::current()->setVisibility(0);
+    GModel::current(b->value() - 1);
+    GModel::current()->setVisibility(1);
+  }
   if(w->window()) w->window()->hide();
   CTX.mesh.changed = ENT_ALL;
   GUI::instance()->resetVisibility();