Have some Shoes questions!

Hello All,

I recently started playing with Shoes to learn it during my Ruby
learning journey.
It appears to be easy, although the current doc is not what a beginner
like I would prefer.
googling around I found a nice website,
http://shoes-tutorial-note.heroku.com/, which has some nice simple
samples programs, just what beginners, like I, need.
On my learning, I heavely borrowed from a program, simple-calc.rb,
listed on the tutorial mentioned above. I hope the developer of this
pgm does not get upset.
I have some questions which I would like help with.

First, should I post Shoes questions to shoes@librelist.org or should
my questions go to ruby-talk@ruby-lang.org? or Both?
I am attaching my image so you can analyze it and comment on it.

1 - When placing a number of buttons, such as the ones found in a
calculator, how can I tell Shoes to place them on the center of the
pane, without having to specify margin?

       flow :width => "100%", :margin => 58 do
               %w(7 8 9 + sin 4 5 6 - cos 1 2 3 * sinh tan cot 0 ln /
cosh Exp log
tanh = Mod n! sqrt x*2 x*y % e Pi Clr Ce).each do |btn|
                       button btn, :width => 46, :height => 46 do
                               method = case btn
                                       when /[0-9]/; 'press_'+btn
                                       when '+'; 'press_add'
                                       when '-'; 'press_sub'
                                       when '*'; 'press_times'
                                       when '/'; 'press_div'
                                       when '='; 'press_equals'

        ect, etc, etc
                               end # case
                       end # button do
               end # each do
       end # flow

2 - I am using a stack do with nothing inside (between the do and the
end) to keep items within a flow one on top of the other, is there a
different way to do this?
       flow :margin => 6 do
               radio; para strong("512b BK")
               radio; para strong("1K BK")
               radio; para strong("MB")
               radio; para strong("GB")
               radio; para strong("TB")

               stack do
               # I am using this as a way to stack up groups.
               # There might be a much better way!

               radio; para strong("Deg")
               radio; para strong("Rad")
               radio; para strong("Grad")
               radio; para strong("DEC")
               radio; para strong("HEX")
               radio; para strong("BIN")
       end # flow

3 - I tried to use the Pi symbol and the square root (√) symbol and
other symbols as caption/lable for the corresponding buttons, but I
got an errors or the wrong thing displayed. Is there a way to
accomplish this?

4 - It looks like I can achieve the same function with para and
caption. What is the difference between the two?

5 - How can I reduce the space between flows?

Thank you for your help!


Ruby Student