Matlab has introduced a modern and more powerful graphics engine called "HG2". It was a mess, that grahpic handles were doubles before, because this let users misuse them as numbers. It seems like your code did that and in consequence it fails now.
The HG1 and HG2 graphics systems are not compatibel. So if you want to run the GUI without changes, you have to start it in an old Matlab version. If you want to run it in a modern Matlab version, adjust the code such the graphic handles are treated as graphics handles.