Sample code for Trimble SketchUp web dialog component. Clicking button, javascript popup message appears. Clicking link, ruby popup message appears.

SketchUpDialog.rb

require 'Sketchup'

def show_dialog
  dlg = UI::WebDialog.new("DialogTest", false,
   "DialogTest", 200, 150, 150, 150, true);
  html = <<-HTML
    <form>
      <input id="start2" onClick="window.alert('alert from javascript');" type="button" size="100" value="input">    
      </br>
      <a href="skp:ruby_messagebox@from link">link</a>
    </form>
  HTML
  
  dlg.set_html html
  dlg.add_action_callback("ruby_messagebox") {|dialog, params|
    UI.messagebox("You called ruby_messagebox with: " + params.to_s)
  }
  dlg.show
end

show_dialog