Minor fixes to 3D preview

lib/Slic3r/GUI/Plater.pm

@@ -531,7 +531,6 @@ sub remove {
     
     $self->select_object(undef);
     $self->update;
-    $self->{canvas}->Refresh;
     
     $self->schedule_background_process;
 }
@@ -548,7 +547,7 @@ sub reset {
     $self->object_list_changed;
     
     $self->select_object(undef);
-    $self->{canvas}->Refresh;
+    $self->update;
 }
 
 sub increase {

lib/Slic3r/GUI/PreviewCanvas.pm

@@ -143,7 +143,6 @@ sub load_object {
             }
         }
     }
-    $self->dirty(1);
 }
 
 sub SetCuttingPlane {