This is because Chrome introduced in version 55 pointer events: https://developers.google.com/web/updates/2016/10/pointer-events
qooxdoo already had a pointer event layer which created artificial events for browsers not supporting pointer events natively. This layer didn't detect chromes new native pointer event support, leading to double fired ponter events, which leads to menu button menues being opened and closed right afterwards with no visible reaction to the user.
This was fixed in qooxdoo github master via PR https://github.com/qooxdoo/qooxdoo/pull/9219
Please also note how this could be fixed for existing qooxdoo 5.0.1 applications: https://github.com/qooxdoo/qooxdoo/issues/9182#issuecomment-265161921
Or you could use current master or patch your local copy manually using the code from https://github.com/qooxdoo/qooxdoo/pull/9219