Hey that is the best trick I've seen in a long time.
I have been using Moom from the app store which is way more useful, at least to me.
I was testing this and it didn't work on my system. Then I realize I'm using Pathfinder and not Finder. Closing Pathfinder and using Finder does the trick.
I can get an edge to snap to a certain extent, but I can't get height to match. There must be some requirements that my system or settings don't meet.
If you double click on the arrow to expand the window, it will expand that side or corner all the way to the edge of the monitor. Room is left for the dock if it's visible.
Thanks for the option-key to bypass the feature. I like having lots of windows open, staggered with some space between them so I have somewhere to click to bring others forward. Neat alignment would destroy my planned chaos.
This doesn't work on my MacBook Pro 13'', mid-2014 model
I was using a 21" iMac with the normal apple mouse. I'm not sure which year, probably late 2014.
Were you using the trackpad for clicking? Maybe there's a setting for it.
Hmm, that's weird - one other person below is having trouble too. There's no interface for it, and I'm using it on an older MacBook Air yet, so the only thing I can imagine is some sort of software conflict.
What has always been missing, of course, is a feature from pre-OS X days, the Special Finder, where folder specific window positions and sizes were remembered from one session to another (http://arstechnica.com/apple/2003/04/finder/3/).
The Special Finder treated windows as objects whose properties were set until you changed them. Thus you could close a Finder window (or restart the computer) and reopen a folder and its window would be right were you left it.
I have used Finder Window Manager since the early days in OS X to control Finder window positions. It enables me to create window sets with windows in specific locations at specific sizes. There are other window management tools out there now but I've seen none that offer this kind of control. Most of them just cut your screen into sections on a grid and/or provide the snapping capabilities newly available in Sierra. FWM is currently available only from MacUpdate (https://www.macupdate.com/app/mac/21475/finder-window-manager) while the developer is upgrading his software. In the meantime, FWM works for me in OS X 10.9.5 Mavericks. I haven't tested it in Yosemite, El Capitan or Sierra. I was afraid development had lapsed; It's a hopeful sign that the developer says he is modernizing his offerings.
Still, window management is one of the Finder's biggest weaknesses. Apple made a stab at fixing things with window tabs, but it's my impression most people don't even know the feature exists—and are unlikely to use it if they do. It's in Apple's genes to abandon a perfectly good feature, like the Special Finder, and never look back. They do the same thing with software, like Aperture. Even Spotlight is more difficult to use than the old Find File from Mac OS 7. I use Find Any File (http://apps.tempel.org/FindAnyFile/)
to restore the ease of use Apple abandoned, which includes displaying found items in a hierarchical list so you can clearly see where they live. The closest you can come to that in Spotlight is to have the folder list displayed at the bottom of a window, with folders that bounce around as you try to uncover their names. It's the very definition of a pain in the butt, bad design personified.
Sadly Apple has long been infected with the change for its own sake virus and shows no signs of getting well. Indeed, they don't even know how sick they are. Though it's not all Tim Cook's fault. He learned hubris from Steve Jobs. With Jonathan Ive hanging around as God's shadow, who is Time to question things? He's an excellent businessman, but he doesn't know squat about design. So though Apple's off the rails in software design, he's not the man to see it, let alone fix it.
Thanks for the FWM link, it looks like I could really use it. I too miss the spacial Finder. As it started going away, I hoped that Pathfinder would be a good substitute, but it had problems with window management, too, though different ones. Tabs are seen as the Answer to Everything, but for anything other than read only, such as a browser, I can't stand tabs (and omniweb tabs beat safari tabs any day). Tabs make it hard to drag and drop, to compare things, or to find what you're looking for.
Snow Leopard is the last system that I've actually liked, even though it killed a quintessential Mac advantage over unix-Type and Creator codes. The loss has cost me much time, fiddling, and swearing ever since. Filename extensions--bah humbug, and get off my lawn...
I've not been able to make this work on an MBP Retina. Is there something I need to check off first?
No, there's no interface to it at all. I'm using it on an older MacBook Air, so I doubt it's a hardware thing. Could you have some other software involved that might be conflicting? Perhaps try in another account or in a Safe Boot?
I'm not sure about a conflict but it's certainly possible. How could I tell if there was one and what was causing it?
Well, as I said, try logging into a different account, or try a Safe Boot (boot with the Shift key down). If you have another startup disk, try that too. Anything to isolate some portion of the current system.
I haven't tried the different acct. solution yet but a Safe Boot didn't do anything at all with the "magnetic folder" situation but it has, seemingly, made the speaker icon show permanently on the desktop and a restart hasn't made it vanish nor has clicking off and the back on the button that allows for it to show up in the menu bar.
When I did a shut down instead it did vanish.
This is really a great feature! I have been using the FREE specticle App find it on github, can't see that changing soon but I see I am using this apple feature everyday now.
I noticed this also works for aligning windows with the edges of the screen.