Something wrong with PyGTK notebook

[NoBugs!]

I noticed a problem with a PyGTK notebook sometimes not selecting the right tab when I use .set_current_page(num). I made a small test to see if this always happens, and this not only doesn't work right, it also causes segfault sometimes! When a tab is clicked, it goes into infinite loop, or sometimes segfaults, if you use the arrow keys it lets you change the tab sometimes, but it still doesn't work as expected. Is there something seriously gone wrong with my pygtk installation or is it a bug in pygtk? or something wrong with this code? Sometimes I start it and it goes into infinite loop, other times it starts fine, then after changing selected tab it goes into infinite loop, it's unpredictable.


#!/usr/bin/env python

# based on example notebook.py

import pygtk
pygtk.require('2.0')
import gtk

class NotebookExample:

def delete(self, widget, event=None):
gtk.main_quit()
return False

def tabChange(self,obj1,obj2,i):
if self.canupdate:
self.canupdate = False
self.newtabs(i) #update it.
print i

def newtabs(self,i):
#remove all tabs
while self.notebook.get_n_pages():
self.notebook.remove_page(0)
#updated tabs:
for n in range(3):
label = gtk.Label(n)
if i==n:
label.set_markup("<b>selected</b>")
self.notebook.append_page(gtk.Label(i),label)
print "added one"
if i==n:
self.notebook.set_current_page(-1) #select this last one.
self.notebook.show_all()
self.canupdate = True

def __init__(self):
window = gtk.Window(gtk.WINDOW_TOPLEVEL)
window.connect("delete_event", self.delete)
self.notebook = gtk.Notebook()
window.add(self.notebook)
self.notebook.connect("switch-page",self.tabChange)
window.show_all()
self.canupdate = False #only one update going.
self.newtabs(0)

def main():
gtk.main()
return 0

if __name__ == "__main__":
NotebookExample()
main()

[NoBugs!]

Tried reinstalling python gtk with synaptic, restarting, it didn't help...
I tried debugging with winpdb, but it keeps freezing when this script freezes :(
How can I see where it crashes with segfault?

[diesch]

When the set_current_page() call in newtabs() generates a switch-page signal, that isn't handled immediately but inserted into the event queue to be handled after newtabs() finished - at which point canupdate is True again.

Also the self.notebook.show_all() selects the first page so that set_current_page() doesn't do much except generating a signal.

You can fix this by removing the if i==n: block and inserting



self.notebook.set_current_page(i)
while gtk.events_pending():
gtk.main_iteration ()
right after self.notebook.show_all()

[NoBugs!]

Thank you very much - I fixed it so the selected tab has the bold, it seems to work but it still has a couple problems:

When I select a tab and press the right arrow key, it usually selects the next tab and makes it bold text, but sometimes another tab gets selected(This gets worse with more tabs, if you change range(3) to range(30) on line 26). Also, when I hold down the right arrow key, it causes a segfault after about 10s. I had this problem earlier with too much tab switching crashing python, though it isn't as bad now:


#!/usr/bin/env python

# based on example notebook.py

import pygtk
pygtk.require('2.0')
import gtk

class NotebookExample:

def delete(self, widget, event=None):
gtk.main_quit()
return False

def tabChange(self,obj1,obj2,i):
if self.canupdate:
self.canupdate = False
self.newtabs(i) #update it.
print i

def newtabs(self,i):
#remove all tabs
while self.notebook.get_n_pages():
self.notebook.remove_page(0)
#updated tabs:
for n in range(3):
label = gtk.Label(n)
if i==n:
label.set_markup("<b>selected</b>")
self.notebook.append_page(gtk.Label(i),label)
print "added one"
#if i==n:
# self.notebook.set_current_page(-1) #select this last one.
self.notebook.show_all()
self.notebook.set_current_page(i)
while gtk.events_pending():
gtk.main_iteration()
self.canupdate = True

def __init__(self):
window = gtk.Window(gtk.WINDOW_TOPLEVEL)
window.connect("delete_event", self.delete)
self.notebook = gtk.Notebook()
window.add(self.notebook)
self.notebook.connect("switch-page",self.tabChange)
window.show_all()
self.canupdate = False #only one update going.
self.newtabs(0)
window.show_all()

def main():
gtk.main()
return 0

if __name__ == "__main__":
NotebookExample()
main()

[StephenF]

I got this stable by using gtk.Notebook.connect_after instead of connect which then runs your callback for replacing the notebook pages after GTK+ has done updating the widget.

Seriously though, I don't understand why you are recreating the notebook pages each time a new page is selected. Consider using gtk.Notebook.set_tab_label_text to change the notebook page title.

[NoBugs!]

Thanks for the tip! Changing it to connect_after("switch-page",self.tabChange) works, it no longer causes segfault after many tab changes, and it selects the correct tab (though it selects a nearby tab sometimes, when I hold down arrow key). No more random tab selection :)

[StephenF]

It selects a nearby tab sometimes, when I hold down arrow key.
What about this? I'm guessing it will behave itself.


#! /usr/bin/env python

"""Numerated selector using a GTK Notebook widget - example."""

import pygtk
pygtk.require('2.0')
import gtk

class NotebookSelector(gtk.Notebook):
orig = None

def cb_switch_page(self, nb, page, page_num):
if self.orig:
self.set_tab_label(*self.orig)
child = self.get_nth_page(page_num)
self.orig = (child, self.get_tab_label(child))
self.set_tab_label(child, self.selected)

def __init__(self, labels=("0",), select_text="<b>selected</b>"):
gtk.Notebook.__init__(self)
for lt in labels:
tab_label = gtk.Label(lt)
internal_label = gtk.Label(lt)
self.append_page(internal_label, tab_label)
tab_label.show()
internal_label.show()

self.connect("switch-page", self.cb_switch_page)
self.selected = gtk.Label()
self.selected.set_markup(select_text)
self.selected.show()


class App(object):
def __init__(self):
window = gtk.Window()
window.connect("destroy", lambda w: gtk.main_quit())
ns = NotebookSelector(("0", "1", "2"))
window.add(ns)
ns.show()
window.show()

if __name__ == "__main__":
app = App()
gtk.main()