Comment 4 for bug 267999

Sorry, should also mention that I've tried the usual tricks I would try under Windows. That is, sometimes under Windows you get the behaviour where the OS gets confused and doesn't recognize a key-release on something like the shift key, and thus when you type it capitalises everything. You get around this by pressing each likely logically "stuck" key and it eventually toggles off.
I pressed each of my shifts, ctrls and alts just in case. No difference.

If I run 'xev', and press 'c' (but with my caps on, which results in a lowercase 'c' due to inversion) I get the following

KeyPress event, serial 31, synthetic NO, window 0x4800001,
    root 0x67, subw 0x0, time 172316092, (-306,483), root:(202,536),
    state 0x0, keycode 54 (keysym 0x63, c), same_screen YES,
    XLookupString gives 1 bytes: (63) "c"
    XmbLookupString gives 1 bytes: (63) "c"
    XFilterEvent returns: False

KeyRelease event, serial 31, synthetic NO, window 0x4800001,
    root 0x67, subw 0x0, time 172316215, (-306,483), root:(202,536),
    state 0x0, keycode 54 (keysym 0x63, c), same_screen YES,
    XLookupString gives 1 bytes: (63) "c"
    XFilterEvent returns: False