RFE: Way to exit when transparent compositor is no supported/enabled

[sztsian]

Description:
A elegant way to exit the danmaQ client is needed when there are no transparent support or transparent compositor is not enabled for the desktop environment.

Environment
Fedora 29, LXQt 0.14.1. Compton not running.

Steps to reproduce:
If I launch danmaQ without compton enabled, the whole screen will be black (with the mouse still visible). I cannot terminate the program in an elegant way. And I have to switch to another console to kill danmaQ.
I know compositor is needed for danmaQ to run, but I still suggest to make it possible for people that happen to run without transparent support to quit in a straightforward way, rather than kill it by command.