In line with DF's option to click the MMB on a window's titlebar to move it to the next monitor, amusingly it also has a habit of doing this on Combobox controls which include the edit line - if the dropdown is extended and you middle-mouse-click on either the first or second line of that popup control, the dropdown itself is actually shunted to the next screen.

For example, the "Search history" edit of many programmes (such as Notepad++, and others) is a common example of such a control, but they may be used for anything, and DF seems to treat them all the same, no matter the programme.

"And why are you clicking there with the MMB?" I hear you ask. Excellent question. It's rather like how one's tongue will always seek out a broken tooth, I strangely can't help myself now that I know it happens. Ok, the real answer is that I was experimenting with an MMB hook myself to copy elements of such on-screen arrays and stumbled upon DF's thoughtful - um - "feature" - and now I just feel compelled everytime I see a dropdown. It's unhealthy.