If you have rootsh installed, your system may to ask you for a password when you run sudo [command]. Some N900s don't do this, some do - it depends on some system settings of other... I never bothered tracking it down, though it's a known issue. This is what explains the previous page's "text doesn't appear when I type password" issue - when you get password prompts in X-Term, it just doesn't show you typed anything. It DOES, however, register all your key presses, so just carefully type your password as normal. If you don't know your password, from X-Term, type:

Because of this, I recommend that you instead add your applications to the sudoers file (don't ask me how I don't know, I just know what doing so would do), and let it run commands that way. OR just have it "sudo gainroot" (only once have I read of that asking for a password on the N900) - and run all your other commands without "sudo".

I can't help on the Qt side of things though. I know a broad range of topics on this forum, only Python marginally well enough to code in it... sorta.