Click on the buttons tab, and you'll see a single trigger is assigned to hard button 4. The '2' indicates that the button must be held down for two seconds to match the trigger. On the right of the blue line are the action category ('Apt') and the action ('Menu'). This tells us that when hard button 4 is held down for 2 seconds, the Apt menu will be displayed. Try exiting Apt (make sure it's enabled on the settings screen first), then hold the button till the menu appears.
Now add a trigger of your own. Select 'Hrd 4' with the left most pulldown menu. The default number of presses is '0', which means that you press and release the button to match the trigger. Notice the default action is 'App' , which means to launch an app. Try picking a different app to launch.
Finally, use the target selector in the top right to pick a different target (Applications in the screenshot). And assign another trigger to hard 4. Press the left most button to increase the repeat count to one, meaning the trigger activates when hard 4 is held for 1 second. Assign Calc to that trigger.
Now go and test the assignments you've made. You should find the following behaviour:
|Any||Hard 4 press and release||Contacts launches|
|Applications only||Hard 4 press and hold 1 second||Calc launches|
|Any||Hard 4 press and hold 2 seconds||Apt menu appears|