Can I disable window resizing from the top edge of the window in Lion?

Solution 1:

Based on mjmt's excellent info, here's how to globally disable resizing (tested in 10.7.4):

defaults write -globalDomain AppleEdgeResizing NO

Log out and log back into your account (or quit every single app) to see changes take effect.

Solution 2:

Lion has (at least for now) the following preference keys:

AppleEdgeResizing (boolean)
AppleEdgeResizeBorderSize
AppleEdgeResizeCornerSize
AppleEdgeResizeCornerSizeNW
AppleEdgeResizeCornerSizeNE
AppleEdgeResizeCornerSizeSW
AppleEdgeResizeCornerSizeSE
AppleEdgeResizeExteriorSize

These can be accessed either with either the following commands:

defaults read DOMAIN KEY
defaults write DOMAIN KEY VALUE
defaults delete DOMAIN KEY

Where DOMAIN can be either -globalDomain to affect all apps, or a specific app's identifier e.g.: com.apple.TextEdit

Or edit ~/Library/Preferences/.GlobalPreferences.plist or other .plist file thereabouts, in Xcode or some other Property List editor.

Apps need to be restarted before they'll recognize any changes.

Solution 3:

Not currently configurable or able to be turned off by any out of the box control or setting.

It's meant to be always on and you'll likely need a third party solution (or a hidden default setting like the other answers have provided) to change the logic behind the resizing.