Ubuntu 18.04.1 LTS Firefox 64.0 (64-bit) Mozilla Firefox for Ubuntu canonical - 1.0 When trying to use shortcuts that use shift key, instead shortcut without it activates: 1)ctrl+shift+t - expected: undo close tab - get: open new tab (same as ctrl+t) 2)ctrl+shift+n - expected: undo close window - get: open new window (same as ctrl+n) 3)ctrl+shift+tab - expected: go one tab to the left - get: go one tab to the right (same as ctrl+tab) 4)ctrl+shift+PgUp - expected: move tab to the left - get: go one tab to the left (same as ctrl+PgUp) 5)ctrl+shift+PgDn - expected: move tab to the right - get: go one tab to the right (same as ctrl+PgDn) 6)ctrl+shift+a - expected: add-ons - get: select all (same as ctrl+a) Also tried ctrl+shift+h, got same result as ctrl+h (history sidebar) Since I don't know how "Library window (history)" should look like I can't say if it is not working correctly. Everything was tested with both shift keys Both shift keys WO-RK Everything was tested in safe mode Shift+left, +right, +up, +down work as expected Since ctrl+PgUp gives functionality of not-working ctrl+shift+tab, I question recognizing the shift key