A red icon indicates a thread that is currently not captive.

A blue padlock indicates that the Code window is attached to this thread.

A gray icon indicates a special thread that is not under the control of RealView Debugger and so cannot become captive (see Special threads in the Thread tab).

When you are working in RSD mode, a yellow icon indicates that a thread is captive, for example after hitting a breakpoint.

The padlock icon is shown if the Code window is attached to the thread, regardless of its captive state.

In HSD mode, a yellow icon indicates the thread that was running when the target stopped.