can't remove a widget correctly from a Gtk::ScrolledWindow

[Jonas Platte]

I've got a little program that should change the content in the left area when an item in a TreeView on the left side of the window is clicked. Everything worked well, until I changed the right areas base container to a ScrolledWindow. Now, when I remove a widget from the right area, and afterwards - somewhen in the runtime - change back to it, it can't be added anymore. I get the error

Gtk-CRITICAL **: gtk_scrolled_window_add_with_viewport: assertion `gtk_widget_get_parent (child) == NULL' failed

I've found a bug report for something that seems to be the same, but in gtkmm 2.4: https://bugs.launchpad.net/ubuntu/+source/gtkmm2.4/+bug/30345

I've got a code sample as attachment that shows the problem. You can also see it when you compile my program yourself (It's available on github: https://github.com/jonessen96/SchoolMessOrganizer)

ProblemType: Bug
DistroRelease: Ubuntu 12.10
Package: libgtkmm-3.0-dev 3.5.12-0ubuntu3
ProcVersionSignature: Ubuntu 3.5.0-15.22-generic 3.5.4
Uname: Linux 3.5.0-15-generic x86_64
ApportVersion: 2.5.2-0ubuntu4
Architecture: amd64
Date: Mon Sep 24 21:36:26 2012
InstallationMedia: Ubuntu 12.10 "Quantal Quetzal" - Alpha amd64+mac (20120905.2)
ProcEnviron:
 PATH=(custom, no user)
 LANG=de_DE.UTF-8
 SHELL=/bin/bash
SourcePackage: gtkmm3.0
UpgradeStatus: No upgrade log present (probably fresh install)

[hermann meyer (brummer10)]

This happen because you remove the viewport instead the button in your example code.
when you call
main_area.add(button_test);
you add a Gtk::Viewport to the scrolled window, the button is then a child of the viewport.
So after the call to
main_area.remove();
you remove the viewport and the button is still a child of the viewport.

[Jonas Platte (jplatte)]

Thanks! :)
I wondered why the remove function doesn't work, if it's just the function from Gtk::Bin and no additional function from the ScrolledWindow class. This is the solution!

Now that opens up a simple way to work around this, but I think this still is a misbehaviour and should be fixed. I already opened a thread in the gtkmm mailing list: https://mail.gnome.org/archives/gtkmm-list/2012-October/msg00002.html so I'll ask there again.