A scroll wheel bug in Designer

I have to try used the scroll wheel item in my design.

I set the Item Template and set number of items to 7, but the code of viewbase.hpp always 4 and viewbase.cpp is 7.

Code is like below.

.hpp :

touchgfx::ScrollWheel scrollWheelFile;

  touchgfx::DrawableListItems<WheelListFile, 4> scrollWheelFileListItems;

.cpp :

scrollWheelFile.setNumberOfItems(7);

How to fix this bug?

Thanks.