Resize windows when add monitor

I just added a 27" monitor for use with my MBP. Is there a way to grow the windows when I plug into the larger monitor?

My main issue is some windows are too short and I’d rather have them lengthen. For Safari, it would be equivalent to Option-Clicking the green button. But for Mail that action fills the screen; I just want it to lengthen. OK, this is the Window>Zoom, but acts differently in two Apple apps.

I know this is a broad question, so a suggestion or two might get me going in the right direction. Probably not practical to have something that covers all cases. Maybe just a macro to grow the window vertically.

Here's a example Action that will stretch the frontmost window to fit the monitor. Maybe this will get you started.

You may need to adjust the SCREEN functions to use something other than "Main".

I got this from a macro library I downloaded from this forum.
I'm searching now to find the source, and will post when I do.

@KBM, here's the macro library I was referring to above:

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Thanks. I think this will do for me. No idea what it means and no idea how I would have found Move and Resize in Resize.

I just used Control-Shift-W, but might look at the number pad. I’ve gotten out of the habit of using it since I abandoned my old iMac, but am using add on keyboard with the monitor set up. Still evolving the setup and will get a different keyboard eventually. I miss the fn key.

Thanks also for sending the macro, I’ll look at it. Well I can’t seem to download it, but I don’t think I need it.

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Download works fine for me.
First, click on the link to the topic, then on the download link.

I get it. That’s a problem with the board app. I clicked on the link I saw.

Wow, you’ve gone far with this.

I’m not sure how you are getting that link, but here is the download link:

I wrote that macro library. Here’s a little more about it:

I like to use every pixel on the screen - when I want to move/resize a window, I usually want some edge of the window to move right to the edge of the screen. Before Sierra, I wasted time trying trying to manually position windows right to the edge of the screen. With Sierra, Apple has done a great job making window borders “snap” to either the screen edges or other window borders. But these macros still work well.

Keyboard Maestro provides powerful window resizing functions. I wanted to use them, but I don’t want to remember complex sequence of keys to move windows around. I’m too dumb.

Numeric keypads to the rescue! I have full external keyboards at home and at work - with numeric keypads. I never use the numeric keypad for numbers, so it’s a beautiful set of keys just waiting to be assigned functions with Keyboard Maestro.

I mapped the keys around the “5” key so that they move windows to the edges, in an obvious pattern. The “7” key moves the current window to the upper left edge of the screen, the “6” key moves the current window to the right edge of the screen, etc. With some modifiers, the same keys move windows and change their sizes such that they “tile” into the 4 corners of the screen.

The “0” key is twice as wide as the other keys, so I made it mean “stretch the current window horizontally as far as possible”. The “enter” key is twice as tall, so it means “stretch the current window vertically as far as possible”.

With if you use the keys with the “shift” key pressed, the meaning changes to “move the window, but also resize it so it takes up half the screen” to nicely “tile” windows.

I use a MacBook Pro laptop, which I carry back and forth between home and work. I have external monitors at home and at work, with different resolutions. So daily, I use 3 screens with different resolutions, depending where I am: home, work and elsewhere (meetings), when I’m using the laptop’s native screen. The macros work the same when I switch monitors. Also, they “know” that I like having the Dock on the left side of my screen, so they have hard-coded offsets to avoid the dock.

I use these keys a lot.

The laptop keyboard doesn’t have a numeric keypad. I made some of the regular keys have the same functionality, when I modify them by holding the control+option+command modifiers. This part of things won’t work out-of-the-box for someone else, because I use the Dvorak key layout, so if you like it, you’ll have to change the trigger keys a bit.


  1. Dock width and position is hard-coded into the macros. If you like a different dock position or size, you’ll have to tweak the macros.
  2. If you want to use the macros on a keyboard without a numeric keypad, you’ll have to tweak the macros.

I work at multiple locations with multiple monitors (it’s not exiting). My MBP goes everywhere. I’ve used Moom for years. It’s small, slick, extremely useful, hard to replace, robust, and a bargain. I’m happy to recommend you try it. I’m just a satisfied customer.

There are a lot of options. Feel free to message me with questions — I’ll answer what I can.)

Moom looks good, but siemsen and KM do the important parts for me. siemsen uses the keyboard in a logical way. I use the keyboard so changed to Command-keyboard num. My use case is a bit more limited, since my main need occurs when I move to the monitor and the keyboard with a numeric keypad.

And one less app to worry about. BTW I’m still running another ManyTricks product, Butler, but KM has almost completely replaced it. One of the few commands left on Butler is opening KM for the times when for some reason it has been quit.