Stefano Facchini authored Oct 20, 2018 and Robert Ancell committed Jul 15, 2019

Since the switches for media, personal file, and screen sharing are in the header bar of the
respective dialogs, they are not visible when we click on the master switch. This caused the
check in OFF_IF_VISIBLE to always fail.

Fix it by checking if the corresponding button in the main list box is visible, instead.

Closes: #240