user29659: How do I use the keyboard to cycle through Arduino windows on a mac?
In my System preferences, I have (default):
Keyboard -> Shortcuts -> Move focus to next window =  Cmd ⌘   ` 
It works perfectly in all other programs, but in the Arduino IDE, it only swaps between the last two windows. If I have three(or more) windows open, it is a real pain to find the one in the background.
I am using fully updated MacOS 10.14 and Arduino IDE 1.8.7

user29659: Just by trying, I found that  Cmd ⌘   Shift   `  cycles through all windows (maybe in reverse).

user313: In MacOS 10.14 and Arduino IDE 1.6.12, cmd` cycles through 5+ IDE windows properly, for me.
Update:

When you upgrade to Arduino 1.8.7,

I won't be. I've tried a couple of its point releases and have given up on it because its launch performance is so p...-poor. Maybe 1.9 will finally fix it.
Sloeber/Eclipse is my serious code-crunching IDE. I keep the A-IDE around for reference and for quick knock-off experiments because it's quick to launch.
Update 2:
The OP asked me to note that he 

found that  Cmd ⌘   Shift   `  cycles
  through all windows (maybe in reverse).

Update 3:

In older IDE the reverse cycling with Shift doesn't work?

It works in both directions for me (shifted/unshifted).

29659: <p>How do I use the keyboard to cycle through Arduino windows on a mac?</p>

<p>In my System preferences, I have (default):</p>

<p><code>Keyboard</code> -> <code>Shortcuts</code> -> <code>Move focus to next window</code> = <kbd> Cmd ⌘ </kbd> <kbd> ` </kbd></p>

<p>It works perfectly in all other programs, but in the Arduino IDE, it only swaps between the last two windows. If I have three(or more) windows open, it is a real pain to find the one in the background.</p>

<p>I am using fully updated MacOS 10.14 and Arduino IDE 1.8.7</p>
 29659: <p>Just by trying, I found that <kbd> Cmd ⌘ </kbd> <kbd> Shift </kbd> <kbd> ` </kbd> cycles through <em>all</em> windows (maybe in reverse).</p>
 313: <p>In MacOS 10.14 and Arduino IDE 1.6.12, <kbd>cmd</kbd><kbd>`</kbd> cycles through 5+ IDE windows properly, for me.</p>

<p>Update:</p>

<blockquote>
  <p>When you upgrade to Arduino 1.8.7,</p>
</blockquote>

<p>I won't be. I've tried a couple of its point releases and have given up on it because its launch performance is so p...-poor. Maybe 1.9 will finally fix it.</p>

<p>Sloeber/Eclipse is my serious code-crunching IDE. I keep the A-IDE around for reference and for quick knock-off experiments because it's quick to launch.</p>

<p>Update 2:</p>

<p>The OP asked me to note that he </p>

<blockquote>
  <p>found that <kbd> Cmd ⌘ </kbd> <kbd> Shift </kbd> <kbd> ` </kbd> cycles
  through <em>all</em> windows (maybe in reverse).</p>
</blockquote>

<p>Update 3:</p>

<blockquote>
  <p>In older IDE the reverse cycling with Shift doesn't work?</p>
</blockquote>

<p>It works in both directions for me (shifted/unshifted).</p>
