Or should content appear as a target element when setting an "on click" button action? I was trying to test by adding a button, and assuming there would be a content -> reload when setting the on click action but content doesn't appear as a choice.
There is no UI for it.
I have used it on a button click like so: dmx-on:click="content.reload()"
You can also make use of static click event and set the JS code.