WizMouse from Antibody Software takes care of an annoying issue in Windows that has only gotten worse as PC screens have grown bigger: the need to click each window before you can use your mouse in it. With WizMouse running, any visible window is active; just mouse over it to activate menus, commands, and links for clicking. Whether windows overlap or are separated by space, WizMouse treats them the same. And not just buttons, either: WizMouse also enables scrolling, even in applications lacking mouse wheel support (though that's an experimental option that can cause "strange behavior" in some systems). WizMouse can also reverse the scrolling direction to simulate Apple's mouse technology.
WizMouse's installer finishes with a Configuration screen offering some additional downloads, which we declined, and some setup options such as Start with Windows, Run as Administrator, and the previously mentioned option to enable mouse wheel commands without mouse wheel support--with the ability to set lines per scroll. The only place we want to see "strange behavior" when using the computer is on YouTube, but we didn't need it to scroll with our mouse (which is actually a Rat). We could also activate an option to toggle WinMouse on and off by left-clicking the program's system tray icon, hide the icon entirely, and bring the scrolling window to the foreground. This last option can be especially useful, but we're glad WizMouse let us decide. A system tray icon accesses WizMouse's menu and opens the Configuration screen. We chose to run WizMouse as an administrator, which enables the software in admin windows, to test a bug fix (it worked, apparently).
It was totally easy to test WizMouse: We simply opened three windows, overlapped them, and rolled our cursor from one toolbar to the next, activating anything clickable as we passed over it. And click we did, too--but the scrolling feature may be better still. Any window our cursor was active in scrolled smoothly, potentially saving a lot of extra clicks when switching rapidly between several open windows. WizMouse is free, so try it and see if it works for you.