Surgeon wrote:
> In order to build GUIs with Ruby, should I learn Tk?

No, there is no need for learning Tk if you do not want to use it. At
http://www.trug.ca/Ruby_GUI_Toolkits you will find some other toolkits
available for Ruby. Most of those toolkits use different ways of `doing
things', learning one does not mean knowing all about the others. Of
course, some general aspects of gui-programming can be learned from using
any toolkit.

> By the way, I have tried to find Tk tutorials and I have seen that all
> of them start with Tcl. Are Tcl and Tk "inseparable" things? If I want
> to use/learn Tk, should I learn Tcl first?

Again, no. Tcl is a programming language like Ruby, Tk is just a toolkit.
For a very short tutorial, see:
http://members.chello.nl/~k.vangelder/ruby/learntk/

Have fun ;-)

-- 
HT de Beer