Getting 'Gtk:ERROR' trying to run WxRuby - ruby

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 :)