Just saw this thread while searching for this error:
GLib-GObject-WARNING **: 11:25:51.393: ../glib/gobject/gsignal.c:1206: no emission of signal "button-release-event" to stop for instance '0x208b5b0
'
I am getting it on linux GTK2 (Manjaro Latest version) and it happens when I right click on a node and add a tab to a ATTabs page control, but it does not happen until I close the tab and I have to click the tabs close button twice. Also interesting is if I click anywhere in the tab sheet that has a form then the tab close button works on the first click.
Also strange is if I add the tab from a tool bar button vs the Tvirtualstringtrees popup menu the tab closes on the first click but that same error shows up in the terminal.
Version of GTK on my Manjaro system is: 2.24.32-1