In macOS the text entry field with keyboard focus has a thick blue (or gray) border. When keyboard focus changes to another text entry field, the border briefly pulsates, presumably to help you find the newly-focused item. If you find this animation annoying you can shut it off by typing this command in Terminal:
defaults write -globalDomain NSUseAnimatedFocusRing -bool NO
You will need to restart SkookumLogger after changing the default. Type the same command with NO replaced by YES to turn animation back on.
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