qt_shortcut.rb

require 'Qt4'

def add_shortcut(widget, key, &block)
  seq = Qt::KeySequence.new(key)

  Qt::Shortcut.new(seq, widget) do |shortcut|
    shortcut.connect(SIGNAL("activated()")) do
      puts "running #{seq.inspect}"
      widget.instance_eval(&block)
    end

    shortcut.context = Qt::WidgetWithChildrenShortcut
  end
end

def popup(message)
  Qt::MessageBox.new { |box|
    box.text = message
  }.exec
end

class Editor < Qt::TextEdit
  def initialize(parent = nil)
    super(parent)
    add_shortcut(self, "Return") { popup "From Editor" }

    @fiber = Fiber.new {
      # if you uncomment the require, Return will input a line break
      # instead of showing the popup.
      #
      # Happens with seemingly any gem that wasn't activated before.

      # require 'yard'
    }

    @fiber.resume
  end
end

class Window < Qt::MainWindow
  def initialize
    super()

    self.central_widget = Editor.new(self)
  end
end

class EventFilter < Qt::Object
  protected
  def eventFilter(obj, event)
    (event.type == Qt::Event::ShortcutOverride).tap { |c|
      puts "event filtered" if c
    }
  end
end

app = Qt::Application.new(ARGV)
app.install_event_filter EventFilter.new

win = Window.new
win.show

app.exec