I can't name any other circumstances in which the keyboard behaves as though the Control key is down when it isn't.

Only when I invoke screen capture by using the global hot key does it behave as though the control key is always down. Likewise, using the menu commands in Preview or the Grab utility works normally. If I try any other way to make a screen capture, it works correctly specifically, if I run '/usr/sbin/screencapture -i ~/Desktop/foo.png' from the terminal, I can select an area of the screen and it is correctly saved to the Desktop. It may be around that time that the bad behavior started.) (I did this because I recall playing with the 'locate' defaults that allows you to specify where the screen shot files are saved I'd made a folder on the Desktop to hold them, but I never got it working properly.

I found all the preferences files named '' (in ~/Library/Preferences and also the ByHost folder) and deleted them, with no effect.

I changed the settings to a different key (F4) with no effect (the screen shot still went to the clipboard).

to the clipboard' is Control-Command-Shift-4. 'Save picture of selected area as a file' is Command-Shift-4 and 'Copy picture.

I checked System Preferences > Keyboard > Shortcuts > Screen Shots and the settings are the defaults (i.e.

But I'm not holding down the control key, and yet I discovered the screen shots are going to the clipboard anyway.

This is hard to google, because most of the hits start with 'I'm pressing command-control-shift-4 and no screen shot appears', to which the answer is 'The screen shot is going to the clipboard don't hold down the Control key'. Here's a puzzle for the forum: as of a few weeks ago, when I press Command-Shift-4, my MacBook Pro makes the shutter sound but no screenshot file is written to the desktop.

Mac screen capture copy to clipboard