I am using an Intuos Pro tablet on macOS Sierra 10.12.1.
I configured two ExpressKeys on my tablet:
Key #1: Presses shift key (for blending)
Key #2: Presses "cmd + z" (for undo)


Pressing Key #1 shows up like this in the tabletlog:
krita.tabletlog: "[       ] ShortcutOverride key: 0x1000020 mod: 0x2000000 text: none"
krita.tabletlog: "[       ] ShortcutOverride key: 0x1000024 mod: 0x2000000 text: none"
krita.tabletlog: "[       ] KeyRelease       key: 0x1000024 mod: 0x2000000 text: none"
krita.tabletlog: "[       ] ShortcutOverride key: 0x1000024 mod: 0x0 text: none"
krita.tabletlog: "[       ] KeyRelease       key: 0x1000020 mod: 0x0 text: none"
krita.tabletlog: "[       ] KeyRelease       key: 0x1000024 mod: 0x0 text: none"

For some reason, there is the 0x1000024 key, which seems to be also sent by my tablet for no apparent reason.


Pressing Key #2 shows up like this:
krita.tabletlog: "[       ] ShortcutOverride key: 0x1000021 mod: 0x4000000 text: none"
krita.tabletlog: "[       ] ShortcutOverride key: 0x1000024 mod: 0x4000000 text: none"
krita.tabletlog: "[       ] ShortcutOverride key: 0x5a mod: 0x4000000 text: none"
krita.tabletlog: "[       ] KeyRelease       key: 0x1000024 mod: 0x4000000 text: none"
krita.tabletlog: "[       ] ShortcutOverride key: 0x1000024 mod: 0x0 text: none"
krita.tabletlog: "[       ] KeyRelease       key: 0x1000021 mod: 0x0 text: none"
krita.tabletlog: "[       ] KeyRelease       key: 0x1000024 mod: 0x0 text: none"


When I am only using Key #1, everything is fine. But as soon as I press Key #2, it performs the undo, but from this point on only Key #2 will respond correctly. Pressing Key #1 shows no action. However it starts working again as soon as I either refocus the window or press a random key (no modifiers) on my keyboard. Apparently, Key #2 leaves the input manager in a messed up state.