xfce4-taskmanager is 0.4.1 when running a windows software, the /proc/XXXX/cmdline is like "C:\windows\system32\services.exe". and xfce4-taskmanager just displays a "C" in the command column. at line 99 in taskmanager-linux.c p = strchr (cmdline, ':'); if (NULL != p) { *p = '\0'; } it cuts off all characters after ':'
Fixed in git.