xbindkeys (xvkbd): stuck CTRL with Debian Stretch

I am using xbindkeys with xvkbd to add some magic to additional buttons on my mouse which I can press with my thumb. For this, I have xbindkeys in my ~/.xsessionrc and the following lines in ~/.xbindkeysrc: "xvkbd -text "\[Control]\[Prior]"" m:0x0 + b:15 "xvkbd -text "\[Control]\[Next]"" m:0x0 + b:13 "xvkbd -text "\[Control]t"" m:0x0 + b:17 This setup was working perfectly for the past two years. After the upgrade from Debian Jessie to Debian Stretch I noticed that the control key sometimes appears to be still pressed after using the mouse button once. As a result, every key action x behaves as Ctrl+x. This also causes the mouse buttons to not work as expected. - Debian 9 Stretch, amd64 - xbindkeys 1.8.6-1+b1 - xvkbd 3.3-1+b1 - Mate + xmonad