Version:           3.2.3 (using KDE 3.2.3, Gentoo)
Compiler:          gcc version 3.3.3 20040412 (Gentoo Linux 3.3.3-r6, ssp-3.3.2-2, pie-8.7.6)
OS:                Linux (i686) release 2.6.3-gentoo-r1

I have many times encountered this situation. An application (say KMail) is maximized. Now I need to save attachments. To do this, I drag and drop them onto a knoqueror window: I open Konqueror (which opens in a small window by default) and so KMail is in the background. Now I see Konqueror and the attachments at the bottom of the screen. I drag the attachment, but KMail goes to the foreground, so I need to move the mouse to the tackbar, wait for Konqueror to popup, and then drop the file. If the application waited a small amount of time to detect a drag and dro action, it coult stay in the background, thus allowing for painless drag and drop between apps.
(BTW this is what XP does).