how does one stop the app running?

Let me count the ways... some of them anyway...with windows

1] Right click on the Tixati icon in the top left corner then click  or type "x"
2] Hold ALT then tap F4
3] Right click on any button on the menubar, i.e. , , ...{? help] etc, then click Exit on the menu
4] Right click on the Tixati icon on the windows taskbar, then click . If it still remains running as indicated by the Tixati icon in the tooltray, r. click that icon then

That should give you a start.

You can terminate Tixati by going to the top bar, (Where home, transfers, channels, search, settings, bandwidth, etc are) and right-click to bring up a menu where "Exit" is at the bottom of.

You can exit by right-clicking the tray button in the bottom-right corner.

You can also use crtl+alt+del and find tixati.exe in the task manager and then end the process.

Now, that wasn't so hard, was it?

FWIW: voice command doesn't work to exit the program, already tried it.  
Tixati replies "Sorry dude, you'll have to wait for a future update for that feature, have a nice day :) "

Is voice control on the list of "to do"?