macoswindow-manager
I often move windows around on the desktop by clicking and dragging them by the title bar. As of Lion, you can resize the window from the top, so if you put the cursor in the top portion of the title bar, the icon turns into resize arrows, when I actually want to move the window, not resize it.
Is there a way to turn this new feature off or customize it so resizing from the top is disabled?
Although it's a paid-for utility (which comes with it's own PrefPane etc), this is a great tool for chucking around your windows. You can also set it up to force windows to certain sizes on a shortcut, which is handy if you want to check out your web pages in a browser at 800x600, etc.
By default, you jut press CtrlCommandup-arrow and you get a little black pop-up window that helps you to move/resize the window that had focus when you pressed the shortcut. (the screen grab includes the PrefPane too).
Are you running any sort of third-party window management software? That's the only reason I can think of that this wouldn't work for you.
I can resize the height of my windows using the arrows on any visible edge, including the top and bottom of a max heigh window, and the diagonals. I tested this with the Dock hidden and visible, on the side and bottom, and with a window with a size exceeding that of the screen. Worked every time.
If you're not running any third-party software that might be interfering with window resizing for some reason, the only thing that comes to mind is that your mouse is very sensitive and you're moving it slightly before the click to resize actually registers.
You might also be interested in Moom. It's a pretty handy window manager that can do things like save preset window configurations for different display set ups, or do one-click window resizing to match a specific size in pixels (which you can bind to a hotkey). It's not a solution to not being able to manually resize, but if you're moving windows around different displays often, you may find it handy. Divvy is another popular app that does some of the same tasks, but I haven't tried it myself.
Best Answer
Based on mjmt's excellent info, here's how to globally disable resizing (tested in 10.7.4):
Log out and log back into your account (or quit every single app) to see changes take effect.