To share, this is a post i found about it (by cphillips)

Additionnal stuff:
http://www.suwiki.org/suwiki/index.php?title=Ruby_Tutorial_-Dialog_Boxes_and_WIN32API%28Advanced%29

the Win32API.so link below wont work
you can get Win32API.so from there
After you install ruby into a folder, say c:\RUBY, then Win32Api.so will be in
c:\RUBY\lib\ruby\1.8\i386-mswin32

the original post:
http://groups.google.com/group/Ruby-API/browse_thread/thread/52ade11766148a57

-The function is called "cleanSlate()".
-It will remove all the menus and the window boarder.
-You need to manually disable any toolbars you dont want.
-Requires win32API.so lib(attached).

NOTES:
-It works by looking for a window named "Sketchup - Untitled".
Therefore it will only work when no model is loaded. You could change
this by editing the ruby.
-It wont fully work at startup because the "Plugins" menu gets created
after the cleanSlate() function is run.

Enjoy
Chris
http://groups.google.com/group/sketchup-Pro-Groups/web/win32API.so
http://groups.google.com/group/sketchup-Pro-Groups/web/cleanSlate.rb

<code>
require "sketchup.rb"
require "Win32API"

def cleanSlate()
#setup win32 calls.
findWindow=Win32API.new("user32.dll", "FindWindow", ['P','P'], 'N')
sendMessage=Win32API.new("user32.dll", "SendMessage",['N','N','N','P'], 'N')
getMenu=Win32API.new("user32.dll", "GetMenu", ['N'], 'N')
getMenuItemCount=Win32API.new("user32.dll", "GetMenuItemCount",['N'], 'N')
getSubMenu=Win32API.new("user32.dll", "GetSubMenu", ['N','N'], 'N')
deleteMenu=Win32API.new("user32.dll", "DeleteMenu", ['N','N','N',],'N')
drawMenuBar=Win32API.new("user32.dll", "DrawMenuBar", ['N'], 'N')
setWindowLong=Win32API.new("user32.dll", "SetWindowLong",['N','N','N'], 'N')

#find the sketchup window pw=findWindow.call(0,"Untitled - Sketchup") #remove the menu menu=getMenu.call(pw) while(getMenuItemCount.call(menu)>0) menu=getMenu.call(pw) deleteMenu.call(menu,0,0x400) drawMenuBar.call(menu) end #force the layout to update. sendMessage.call(pw,0x0047,0,"") #remove the window boarders setWindowLong.call(pw,-16,0x00800000|0x10000000|0x00080000|0x00040000)

end
</code>