Just pasted your Tk example into some Perl I was writing, and it ran right away, right out of a Windows command window. Then I tried to add an Exit button. No sweat! It worked. I've never looked at Tk before so it MUST be easy, at least at this trivial level. So I'm convinced, and will learn more.
BTW it looked "Windows" to me, but a bit dated; more Win 3.1 than XP. But I don't like the XP style anyway :-)