private void ClearOverlay(ImageViewerAddOn imageViewerAddOn) { try { // Clear the overlay Guid shapeID; if (_dicShapes.TryGetValue(imageViewerAddOn, out shapeID)) { ClientControl.Instance.CallOnUiThread(() => imageViewerAddOn.ShapesOverlayRemove(shapeID)); _dicShapes.Remove(imageViewerAddOn); } } catch (Exception ex) { EnvironmentManager.Instance.ExceptionDialog("ImageViewerAddOn_ClearOverlay", ex); } }