I have a Macbook Pro (Retina) with an external 4K display. I'm running it with the lid closed, i.e., the external display is the only display. OS X 10.9.5.

Normally, it works fine. The past couple days, when I try to resize a window, the window jumps to a different part of the screen, sometimes.

For example, Mail's main window puts itself in the top-right corner. I can move it back to the left side of the screen, but when I try to resize it, as soon as I start to drag the corner, the entire window jumps back to the top right corner of the screen.

Simply moving windows, though, still works correctly.

Short of rebooting (ugh), is there any way to reset OS X's internal concept of how windows should resize?

UPDATE: I unplugged the external display, and it's still happening with the built-in display.

2 Answers 2


For me, a temporary fix for this is restarting the Dock. Open Activity Monitor, search for "Dock" and force quit the process. Some users in a thread in the Apple discussion forum also suggested hiding and un-hiding the Dock (press Cmd ⌘ Opt ⌥ D twice) might fix it, but I haven't tested that.

  • 1
    Hiding then unhiding the dock didn't work for me, but killing the Dock process did work.
    – Heath
    Commented May 23, 2016 at 15:56

I had a similar issue when using a second display on El Capitan on a macbook pro. When resizing windows in the second display they would jump to my primary display. Doing a safe mode boot then a regular restart fixed it for me.

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