I keep accidentally losing the window by dragging past the bottom of the "screen" and letting go.
The window layout manager is smart enough not to let you push the window totally off the screen, but if you grab a window and pull it down under the taskbar (assuming the taskbar is in the default bottom position and does not autohide) in Windows 7, you're somewhat boned because while the window is still there, the taskbar's zorder makes it impossible to click on it to recover it. You can fix this situation by unlocking the taskbar (if it is locked) and moving it or by setting it to autohide, but neither of these things is a particularly intuitive move for the average user, I'd guess.
On Windows 7 this is not an issue as the windows snap to the sides and top, and if you drag towards the bottom of the screen there are several pixels on the titlebar where you can only resize the window and not move it, it is really difficult to lose a window by dragging it as shown on the website.
I'm not suggesting you're wrong here, just that I've never seen the behavior you're seeing and I use Windows 7 frequently. Perhaps you have some option set that I do not.
On a single monitor setup it captures the mouse and prevents this issue.