Freeze during Debugging of User Interface Components on X11

Problem

• IntelliJ IDEA freezing X11 session when hitting breakpoints set at a User interactable component such as
  • Swing comboBox or JComboBox
  • AWT Components

Environment

Commonly in X11 window system-based Linux OS such as Ubuntu

Cause

When a Java application grabs input events for GUI actions like pop-up menus, other applications receive no input. If a debugger hits a breakpoint during this grab, the OS appears to hang. The Java app is stopped, unable to process events, while others are blocked by the grab. This happens because the Java application holding the grab is stopped by the debugger and cannot process any input events, and other applications do not receive the events due to the installed grab.

Resolution

To allow debugging such applications, add the following parameter to the VM options field of your run configuration.

-Dsun.awt.disablegrab=true 

Reference: Hangs During Debugging of Pop-up Menus and Similar Components on X11