Part 1 of 3 for T7841: Revamp buttons on the bottom to solve various usability issues
CCBUG: 386163
FIXED-IN: 18.04
Spectacle's main window doesn't need a discard/quit button, because there's already a user-visible way of closing the window: the titlebar's close button. The escape key does it, too. This button duplicates existing functionality and takes up room that could be used for a "Configure..." button, and has led to user confusion in the past as well (see https://bugs.kde.org/show_bug.cgi?id=386163)