This bug seems to have existed for a very long time, but it is unlikely many people have noticed it. Steps to reproduce: 1) Open thunar window (preferably with the user's home folder), switch to tree view. 2) In this window, using the menu or any other GUI widget that can do it, open a new window. 3) Close this new window (it is best to leave its tree view alone for easier reproducing the warning). 4) In the old window, click on the expander of the root filesystem. Behold the following warning repeated many times (how often will probably depend on the number of nodes that get opened): GLib-GObject-WARNING **: invalid unclassed pointer in cast to 'ThunarTreeView' Something messes with the view in the original window. I have not found out what that is, but from some observation it does not look like the view is finalized prematurely etc. This does not happen when opening and closing a new tab, only when opening and closing a new window. It might be something in thunar-window, but so far my search has been futile.
Just found out that this one is a duplicate of Bug #14714 ... I explained there what is going on / why the tree-view ref got invalid. Will close this one, since I already added a patch on 14714. *** This bug has been marked as a duplicate of bug 14714 ***