I just ran an interesting scenario.
I opened up Myrlyn (Leap 16.1). I opened up the Configure Repos dialog.
I opened a Konsole terminal. I ran “zypper lr -d” and copied output to Kate (editor).
Back at the Configure Repo dialog, I clicked on Enable for the “Source” Repo. I jumped back to the terminal and executed “zypper lr -d” again (copied output to Kate).
The Source Repo is Enabled immediately - the change is made at the moment you do so.
So, I clicked the “Enable” box about 4 more times, and each time I clicked the box, I did a “zypper lr -d” … and the change each time was immediate. I never exited Myrlyn.
My last quick test was I clicked Enable box one more time, to remove the check-mark (to disable). I switched back to the terminal and typed “xkill” and clicked on Myrlyn’s titlebar to instantly kill Myrlyn. The Source Repo is still disabled … and when I started Myrlyn, it showed no checkmark (as it should) and did not report an error (because it was killed).