Temporarily?

Do you have Default Folder X or Rescue Time installed? Any display link programs like Display Link, Duet Display, or Twomon?
Support

OK. We will try to reproduce the problem on El Capitan, but I have a hunch it's related to some interaction with other software.

Could you try starting it from the terminal? Simple fire up the Terminal app, then execute

/Applications/Spine/Spine.app/Contents/MacOS/Spine

Please post the output on the terminal here. Please also post the content of your log files located in <user home folder>/Library/Application Support/Spine/spine.log

I've created two issues here:

Flashing on resize on macOS · #129 · EsotericSoftware/spine-editor
Editor refuses to start from macOS dock · #130 · EsotericSoftware/spine-editor

I can not reproduce the "can't start from dock" issue on my end, on either El Capitan or Sierra. The logs you provided look OK to me. I did however notice that starting Spine (and other apps like Slack, Chrome, etc.) on Sierra takes longer to show the initial UI.

For the resize flash, we'll have to talk to the GLFW guys who provide the OS bindings for window and OpenGL context management.

Could you elaborate on the hierarchy view not being resizable? I don't see a reason for that not working http://sht.tl/WXvVNV

I work on a dual monitor setup on macOS Sierra 25% of my time. I'm using spotlight to fire up Spine, and have essentially banished the dock from my workflows. However, I tried reproducing the dock issues, but couldn't so far. Did you install Spine in /Applications or somewhere else?

I get the issue with the tree view now. I assume you want it to fill up the entire right side like at 0:24 in the video. Here's the funky part, i got exactly that setup O_o http://sht.tl/lMciAY. I tried minimizing/closing in various permutations, but it always ended up like in the image above.

I have a feeling you are the unluckiest Spine user I keep investigating the dock issue. I got a second Mac machine I can test on later this week.

Regarding the tree, when you move the tree next to the dopesheet, it splits the dopesheet. If you want the tree to be the full height, you just need to move the dopesheet, not the tree. This is the same way splitting panes are moved around in most programs.

Could you give the latest beta 3.5.13 a try? The flashing should be gone.

Ha, I'll remove those right meow!

Unfortunately we probably can't improve the flashing much, not until we revamp our windowing. We have plans for that, but lots of things need to come first.

As for not launching, it's bizarre that we don't see the same issue having tested Spine on many Macs. This makes it near impossible to fix, as it could be almost anything during initialization. Since it doesn't seem to happen on a fresh OS X, I expect there is some OS X configuration or other software interacting with Spine. I'm not sure what we can do to reveal more details about the problem. There shouldn't be anything different about launching from the dock, though that is our best clue.

One last ditch effort to resolve the dock problem: Could you open the "Console" App, select "system.log" on the left, then click the "Clear" button at the top of the window, then launch Spine. Wait until it doesn't launch and freezes, and post the output in the Console app here please.

I've always had problems with Spine loading on OSX. For me, I've found the problem is related to TotalSpaces 2, a utility app. If I'm having loading problems, I've found that if I keep the window focus on a Finder window as Spine is starting, it will more-often load successfully.

It's very annoying, but something I have to live with.