Binding Synapse shortcut to key-release instead of key-press

Question

Background

So I've already referred a question that demonstrates how to bind the Synapse launcher to the "Super (Win) Key". (Can I change Synapse shortcut to Super/Windows key alone?)

The problem is that combinations involving the Super key now all launch Synapse.

I believe this is happening because Synapse is being activated on the button-press event rather than on the button-release event as would happen with, say, Unity or while using it on Windows.

Question

Is there any way in Ubuntu to bind a shortcut to the button-release event? That way I can use the Super button in other combinations, like "Super + D" for show desktop or something.

Environment

I'm using the Gnome (Compiz) Flashback session environment on Ubuntu 14.04 LTS.

Answer 1

ksuperkey worked well for me. I followed the instructions here:

https://blog.hanschen.org/2012/10/17/open-application-launcher-with-super-key/

Except, I'm on Ubuntu 16.04 + MATE, so what I did was:

a) Removed Alt+F1 as the shortcut for the MATE menu in Preferences --> Hardware --> Keyboard Shortcuts

b) Set Alt+F1 as the Synapse shortcut:

cat ~/.config/synapse/config.json       {
          "ui" : {
            "global" : {
              "ui-type" : "default"
            },
            "shortcuts" : {
              "activate" : "<Alt>F1"
            }
          }
        }

c) Installed and ran ksuperkey

ksuperkey now does the mapping from the release of the Win key (Super key) to Alt+F1, which triggers MATE to launch Synapse. At the same time, other combinations involving Win work fine without invoking Synapse. (In particular, I set up Win + M to minimize all windows and show the Desktop and that's important to me).

Note that ksuperkey is quite flexible and the can map the release of any key to send any key combination, not just Alt+F1 (the default).

d) Added ksuperkey to Startup Applications