Hi Pascal,
Please apply the attached patch(LazFiles.zip), then test the attached project(ThreadName.zip). The patch modifies the following files, please do backup before start:
$(LazarusDir)\components\debuggerintf\dbgintfdebuggerbase.pp
$(LazarusDir)\debugger\threaddlg.pp
$(LazarusDir)\ide\debugmanager.pas
With the patch, I also attach the units if you need them. After IDE rebuild, open the project, put a break point in the thread execute method, run the project then press the "Create thread" button.
You should see the thread name as in the attached screenshot. Tested with 64 bit Lazarus too.
regards,
GetMem