Yes there is. I purposely didn't include it in Hack Builder because it's slightly dangerous to remap that button. I have my own reader modified in the same way.
In applicationStart.xml change:
Code:
<boolean key="kSuspend" do="doSuspend"/>
to:
Code:
<boolean key="kSuspend" do="doQuit"/>
I warn you, however. Don't change it to anything else unless you're not afraid of temporarily bricking your reader.