REFERENCE: Detailed description & analysis @ Awesome WM Bug list, Issue 1752: . . . [ https://github.com/awesomeWM/awesome/issues/1752 ] REFERENCE upstream: ... QtQTBUG-60394 ... QTBUG-49952 revived: ... Any USB event :: QT 5.7.1 "eats up" background mouse events ... from all other screens. ... [ https://bugreports.qt.io/browse/QTBUG-60394 ] REFERENCE Pre-Decessor: . . . QtQTBUG-49952 . . . (Un)plugging an input device makes Qt select input events . . . on the root window. . . . [ https://bugreports.qt.io/browse/QTBUG-49952 ]
According to QTBUG-60394, this code has been significantly refactored and the problem may therefore no longer exist. They also advised not to use QT_XCB_NO_XI2_MOUSE. Feel free to reopen that upstream bug if the problem persists under both those conditions.