Getting 'Gtk:ERROR' trying to run WxRuby

Question

I'm using Ubuntu 10.04 and I'm trying to run a WxRuby example which I copy-pasted from this site WxRubyWiki. I've been looking for help over the net but I couldn't find anything similar...

I'm getting this error...

Gtk:ERROR:/build/buildd/gtk+2.0-2.20.1/gtk/gtkwindow.c:6789:IA__gtk_window_present_with_time: assertion failed: (widget->window != NULL)
Aborted

These are the versions I'm using...

ruby -v
ruby 1.8.7 (2010-01-10 patchlevel 249) [i486-linux]
gem list
...
wxruby (2.0.1 x86-linux)
...

And this is the code I'm trying to run...

require 'rubygems' if RUBY_VERSION < '1.9'
require 'wx'

class EventFrame < Wx::Frame
    def initialize()
        super(nil, -1, "Event Frame")
        @idleCounter = 0
        evt_close {|event| on_close(event)}
        evt_idle {|event| on_idle(event)}
        evt_size {|event| on_size(event)}
        evt_key_down {|event| on_key(event)}
        evt_left_down {|event| on_left_down(event)}
        # You can still process these events, you just need to define a separate callback for middle_down and right_down
        # to process them as separate events
        evt_middle_down {|event| on_middle_down(event)}
        evt_right_down {|event| on_right_down(event)}

        button = Wx::Button.new(self, -1, "Push me")
        evt_button(button.get_id()) {|event| on_button(event)}

        show()
    end

    def message(text, title)
        m = Wx::MessageDialog.new(self, text, title, Wx::OK | Wx::ICON_INFORMATION)
        m.show_modal()
    end

    def on_close(event)
        message("This frame will be closed after you push ok", "Close event")
        #close(true) - Don't call this - it will call on_close again, and your application will be caught in an infinite loop
        # Either call event.skip() to allow the Frame to close, or call destroy(), as follows
        destroy()
    end

    def on_idle(event)
        @idleCounter += 1
        if @idleCounter > 15 # Without the counter to slow this down, Idle events would be firing every second
            message("The system is idle right now", "Idle event")
            @idleCounter = 0
        end
        event.request_more() # You must include this, otherwise the Idle event won't occur again
    end

    def on_size(event)
        size = event.get_size()
        x = size.x
        y = size.y
        message("X = " + x.to_s + ", Y = " + y.to_s, "Size event")
    end

    def on_key(event)
        message("Key pressed", "Key Event")
    end

    def on_left_down(event)
        button = ""
        if event.left_down()
            button = "Left"
        end
        message(button + " button was clicked", "Mouse event")
    end

    def on_middle_down(event)
        # This method hasn't been implemented yet...
        #if event.middle_down()
           #button = "Middle"
        #end
        message("Middle button was clicked", "Mouse event")
    end

    def on_right_down(event)
        # This method hasn't been implemented yet...
        #if event.right_down()
            #button = "Right"
        #end
        message("Right button was clicked", "Mouse event")
    end

    def on_button(event)
        message("Button was clicked", "Button event")
    end
end

class MyApp < Wx::App
    def on_init
        EventFrame.new()
    end
end

MyApp.new.main_loop

Thanks in advance!

Answer 1

It is more of an understanding of how GTK+2/wx/wxRuby works. As is, the code above does not work on your configuration in a Virtual Box machine I set to test this nor my development machine's Ubuntu 11.10 x86_64 with 1000Hz kernel compile option and ruby 1.9.3 p21.

The GTK+2 error occurs when the on_size event fires during frame creation. The creation is not yet complete so the message box does not have a parent at that time. You can test this by commenting out (in def on_size(event):

message("X = " + x.to_s + ", Y = " + y.to_s, "Size event")

and trying:

puts "Size event: X = #{x}, Y = #{y}"

to see the event details on standard out. You will notice there are two events fired during creation; an initial size event and a resize event

Another caveat is the idle loop which locks Unity o my system. You can test that the idle event is happening without a lock up by changing the code as below:

in def initialize add this before show():

create_status_bar(2)
self.status_text = "Welcome to wxRuby!"

then in idle_event:

def on_idle(event)
  @idleCounter += 1
  #if @idleCounter > 15 # Without the counter to slow this down, Idle events would be firing every second
  #    message("The system is idle right now", "Idle event")
  #    @idleCounter = 0
  #end
  set_status_text @idleCounter.to_s, 1
  event.request_more() # You must include this, otherwise the Idle event won't occur again
end

A last caveat about the code is you may notice you don't see the key or mouse down events creating their message box. That is because the button control fills the client area and traps the frame events for keys and buttons. If you resize the frame while the app is running the button will not resize with it by default (GTK+2 platform). If you then click inside the frame client area but not on the button you will see mouse events.

Good Luck !

Answer 2

this fixed and works in ubuntu 11.10 :)