JFrame crashes during Debug Mode, even tho eclipse can handle it

Dear community people,

i was trying to debug a program where i use a JFrame with an JPanel added to it. The class from where i start extends Applet.

So i tried to debug it as normal Java application, and as Applet. But somehow the Debug crashes the JFrame from the first time i paint something into it.

But it cannot be my program, because if i run it, the frame works perfectly fine, with no crash or lag.

And on the other hand, i can debug it in eclipse, without any problems as normal Application.

Currently i use the newest version of IntelliJ IDEA Ultimate, but also in the version 2017.3.5 it did not work.

Hope someone can help me,

best regards,

Luca