diff --git a/src/src/measure/ActorDraggableInteractorStyle.cpp b/src/src/measure/ActorDraggableInteractorStyle.cpp
index aab479e..3f52f62 100644
--- a/src/src/measure/ActorDraggableInteractorStyle.cpp
+++ b/src/src/measure/ActorDraggableInteractorStyle.cpp
@@ -99,11 +99,8 @@ void ActorDraggableInteractorStyle::ColorMapping()
 
 	vtkRenderWindowInteractor* rwi = this->Interactor;
 	this->ScalarCurrentPosition[1] = rwi->GetEventPosition()[1];
-
-	//pos[0] = (this->ScalarCurrentPosition[0] - this->ScalarStartPosition[0]);
 	double total = 0.01 * ((this->ScalarCurrentPosition[1] - this->ScalarStartPosition[1]) / scalarSensitivity);
 	double left = total - ConsumedOpacity;
-	//printf("ColorMapping:%d,%d,%.2f \r\n", ScalarCurrentPosition[1], ScalarStartPosition[1],left);
 	if (abs(left) >= 0.01) {
 		OpacityTrigger = true;
 		this->InvokeEvent(ScalarOpacityEvent, &left);
@@ -114,7 +111,7 @@ void ActorDraggableInteractorStyle::ColorMapping()
 
 void ActorDraggableInteractorStyle::EndColorMapping()
 {
-	if (false == OpacityTrigger)
+	if (!OpacityTrigger)
 	{
 		this->InvokeEvent(ScalarShiftEvent, nullptr);
 	}
@@ -165,6 +162,11 @@ void ActorDraggableInteractorStyle::NoneStatePick() {
 				p->AddPickList(obj);
 				p->Pick(pos[0], pos[1], 0.0, this->CurrentRenderer);
 				int* ijk = p->GetPointIJK();
+				//TODO: sometimes ijk will have value less than 0;need to fid out the reason
+				//Firstly: simple fix by set value to 0
+				for (int i = 0; i < 3 ; i++){
+				    ijk[i] = ijk[i]<0?0:ijk[i];
+				}
 				std::string message = "X:";
 				message += vtkVariant(ijk[0]).ToString();
 				message += " Y:";